,,transcriber',s ,,note ,in the numerous chemical formulae a subscripted number is shown as #b1 so the familiar formula for water would be ,h#b,o3 ,h1 subscript #b1 ,o4 ,this notation is needed to distinguish digits that are subscripts from digits that are multipliers1 as for example in the formula ,pb7,,oh7#bb,pb,c,o#c1 where the subscript #b must be distinguished from the quantity multiplier #b that follows it4 ,illustration3 ,frontispiece ,,stoneware ,,made ,,by ,,the ,,author4 ,the ,potter's ,craft ,a ,practical ,guide for the ,studio and ,workshop ,by ,,charles ,f4 ,,binns ,director of the ,new ,york ,state ,school of ,clay-,working and ,ceramics ,some time a ,superintendent in the ,royal ,porcelain ,works1 ,worcester1 ,england ,,second ,,edition ,,second ,,printing #bf ,,plates ,,and #bj ,,text ,,illustrations ,colophon ,,new ,,york ,d4 ,,van ,,nostrand ,,company1 ,,inc4 ,,eight ,,warren ,,street ,copyright1 #aiaj1 #aibb by ,d4 ,van ,nostrand ,company ,all rights reserved1 including that of translation into the ,scandinavian and other foreign languages4 ,printed in the ,united ,states of ,america ,,lancaster ,,press1 ,,inc4 ,,lancaster1 ,,pa4 ,a book is written1 not to multiply the voice merely1 not to carry it merely1 but to perpetuate it4 ,the author has something to say which he perceives to be true and useful1 or helpfully beautiful4 ,so far as he knows1 no one has yet said it2 so far as he knows1 no one else can say it4 ,he is bound to say it clearly and melodiously if he may2 clearly1 at all events4 --,ruskin4 ,,preface ,,to ,,second ,,edition ,since the publication of the first edition of this book eleven years have elapsed1 years packed full of varied and interesting experiences4 ,during that time it has been the pleasant fortune of the author to conduct classes1 especially summer classes1 in the science and art of pottery production4 ,these have been occasions of meeting many fine and noble personalities whom to know is a liberal education4 ,as one of the consequences of these experiences the book has been revised and some new chapters have been written4 ,especial acknowledgments are due and are gratefully made to ,elsie ,binns for the chapter on ,clay-,working for ,children and to ,maude ,robinson for that on ,alkaline ,glazes4 ,the photographs are by the ,taylor ,studios1 ,hornell1 ,n4 ,y4 ,c4 ,f4 ,b4 ,alfred1 ,new ,york4 ,march1 #aibb4 ,,preface ,,to ,,first ,,edition ,this ,book is the outcome of an experience extending over a period of thirty-six years4 ,twenty years ago it would have been impossible1 for the science of ceramics was not then born4 ,ten years ago it would have been wasted for the ,artist-potter in ,america had not arrived1 but now the individual workers are many and the science is well established4 ,written teaching must be imperfect1 but ,i have endeavored to set down the exact methods by which my students are taught1 in the hope that those who cannot secure personal instruction may read and understand4 ,as far as possible didactic statements have been avoided and the attempt has been made to lead every student to experiment and to think for himself4 ,in other words1 ,i have tried to erect sign-posts and occasional warnings rather than to remove all obstacles from the road4 ,c4 ,f4 ,b4 ,alfred1 ,n4 ,y4 ,january1 #aiaj4 ,,contents ,introduction4--,the ,present ,need xiii ,,chapter ,i4 ,applied ,art #a ,,ii4 ,pottery #i ,,iii4 ,porcelain #bc ,,iv4 ,the ,nature and ,properties of ,clay #bi ,v4 ,the ,preparation of ,clay #cg ,,vi4 ,mold-,making and ,plaster #dc ,,vii4 ,cases and ,working ,molds #eh ,,viii4 ,building by ,hand #fh ,,ix4 ,the ,potter's ,wheel #gd ,x4 ,turning #ii ,,xi4 ,making ,large ,pieces #ajg ,,xii4 ,cups and ,saucers and ,plates #abd ,,xiii4 ,casting #abi ,,xiv4 ,tiles #acc ,,xv4 ,glazes and ,glazing ,part ,i #adj ,part ,,ii--,matt ,glazes #aeb ,part ,,iii--,fritted ,glazes #aeg ,part ,,iv--,recipes #afj ,part ,v--,the ,defects of ,glazes #afd ,part ,,vi--,alkaline ,glazes #afg ,,xvi4 ,decoration #agc ,,xvii4 ,the ,fire #agi ,,xviii4 ,high ,temperature ,wares #ahh ,,xix4 ,clay-working for ,children #aid ,,index #bja ,,list ,,of ,,plates ,frontispiece4--,stoneware made by the ,author4 ,,plate4 ,,page ,i4 ,throwing4--,lesson ,,ii1 #a #hj ,,ii4 ,throwing4--,lesson ,,ii1 #b #ha ,,iii4 ,throwing4--,lesson ,,ii1 #c #hb ,,iv4 ,throwing4--,lesson ,,iii1 #a #hc ,v4 ,throwing4--,lesson ,,iii1 #b #hf ,,vi4 ,throwing4--,lesson ,,iv1 #a #hg ,,vii4 ,throwing4--,lesson ,,iv1 #b #hi ,,viii4 ,throwing4--,lesson ,v #ij ,,ix4 ,throwing4--,lesson ,,vi1 #a #ib ,x4 ,throwing4--,lesson ,,vi1 #b #ic ,,xi4 ,throwing4--,lesson ,,vii #ie ,,xii4 ,throwing4--,lesson ,,viii1 #a #if ,,xiii4 ,throwing4--,lesson ,,viii1 #b #ig ,,xiv4 ,making ,large ,pieces4 ,the ,first ,section #aji ,,xv4 ,making ,large ,pieces4 ,measuring the ,foundation of the #aaj ,second ,section ,,xvi4 ,making ,large ,pieces4 ,drawing up the ,second ,section #aaa ,,xvii4 ,making ,large ,pieces4 ,shaping the ,third ,section #aab ,,xviii4 ,making ,large ,pieces4 ,the ,three ,sections ,completed #aac ,,xix4 ,making ,large ,pieces4 ,turning the ,edge of the ,first #aad ,section ,,xx4 ,making ,large ,pieces4 ,finishing the ,bottom of the ,first #aaf ,section ,,xxi4 ,making ,large ,pieces4 ,checking the ,size of the ,second #aag ,section ,,xxii4 ,making ,large ,pieces4 ,fitting ,together ,dry #aai ,,xxiii4 ,making ,large ,pieces4 ,setting the ,third ,section in ,place #abj ,,xxiv4 ,making ,large ,pieces4 ,the ,three ,sections ,set ,together in #aba the ,rough ,,xxv4 ,making ,large ,pieces4 ,the ,finished ,vase #abb ,,introduction3 ,,the ,,present ,,need ,many times it has been proven1 in the history of the world1 that it is not possible to force a reform or a novelty upon an unwilling people4 ,such things are organic4 ,in order to live they must grow and in order to grow must live4 ,no attempt will be made1 therefore1 in these pages to foster an idea or propound a thought which may exist only in the predilection of the author4 ,the trend of the present demand1 a persistent growth of several years1 is towards a personal and individual expression in the crafts or industrial arts4 ,this tendency is the natural swing of the pendulum from the machine-made product of the manufactory which in its turn was the inevitable result of mechanical invention4 ,when the artisan was an artist and the designer a craftsman1 there was but a limited production of industrial art4 ,the articles made were expensive and for the wealthy alone4 ,the common utensils necessary to the household were made on the farm and were of the rudest possible character4 ,but with the gradual development of machinery there came an abandonment of rural activities1 a flocking to the city1 manufacturing on a large scale1 lower prices1 and a huge output4 ,this has1 of course1 taken many years to develop1 but the utmost limit of the swing has been reached and the question is ,what next8 ,will the factory cease its labors8 ,will output decrease in bulk and improve in quality8 ,will there ever1 in a word1 be a return to medieval conditions8 ,not only may all these questions be answered in the negative but it may be stated with all sincerity that there is no need for any other answer4 ,what then1 are not manufactured products as now put forth a menace to the art life of the nation8 ,are not the people being educated in the use of and belief in machine-made ornament and meretricious display8 ,perhaps so1 but no good purpose will be served by a ruthless condemnation of these things4 ,art appreciation is a most subtle thing and no one may dictate to his neighbor as to what he should or should not admire4 ,it took time for the public to understand and patronize the product of the machine even though the price was favorable4 ,it will take time for an appreciation of craftsmanship to influence the land but this consummation will most assuredly come4 ,on the one hand there is the manufactory1 teeming with hands1 riotous with wheels1 turning out its wares by the thousand and supplying the demand of the many2 on the other1 there is the artist-artisan4 ,he labors at his bench in sincere devotion to his chosen vocation4 ,his work is laborious and exacting1 he can make but a few things and for them he must ask a price relatively high4 ,both these conditions are necessary4 ,the craftsman cannot supply the need of the people and the manufacturer has no time or thought for disinterested production4 ,herein lies the need and here is the mission of the individual worker4 ,in every age it is given to some to discern more than the multitude and it is theirs to teach4 ,the people are anxious to learn1 are eager to be led4 ,what they demand will be manufactured and so by the irresistible lever of public opinion the man at the bench1 if he be true to himself and to his craft1 may move the millionaire manufacturer to make wares which1 if not truly artistic1 shall at least be inoffensive4 ,such a mission is not to be accomplished without suffering4 ,the man who essays to attack a giant must be sure both of his ground and of his personal condition4 ,he who would establish his craft in the knowledge and affection of men must possess enthusiasm1 skill1 discrimination and infinite patience4 ,it is not enough to discern the good1 the hand must follow the brain with diligent care4 ,furthermore1 it is not enough to be able to make things well1 one must also make them good and know it4 ,the artist-artisan must have courage to destroy that which is below standard1 and self-denial to resist the temptation to sell an unworthy product4 ,the country needs craftsmen of this type and for them there is an important work4 ,for such1 if they elect to join the ranks of the potters1 these words are written and in the hope that some may be stimulated1 encouraged1 guided and helped the counsel of a fellow craftsman is offered4 ,,chapter ,i3 ,,applied ,,art ,it is not intended1 in these lines1 to consider what are generally termed the ,fine ,arts1 painting and sculpture4 ,these are perfectly competent to take care of themselves and1 indeed1 the author can make no claim to an ability to discuss them4 ,in the field of applied art1 however1 there are certain principles to be observed1 principles1 moreover1 which are frequently lost sight of because of the lamentable separation of the functions of the artist and artificer4 ,it is extremely difficult to draw the line between art and manufacture4 ,for example1 a wall paper1 designed with skill and executed by machinery in actual reproduction of the work of the designer2 is it a work of art or is it a product of the factory8 ,it is both4 ,primarily a work of art is the product of the artist's own hand4 ,it reveals his individuality4 ,it is the language in which he expresses himself to his audience4 ,it is the note of his voice4 ,such a work may or may not appeal to a large section of the public4 ,this will always be so4 ,an artist1 be he poet1 musician1 painter or craftsman1 is one who can see more than others4 ,what he sees he endeavors to express but it is inevitable that he be sometimes misunderstood4 ,hence it the more necessary that his message be delivered at first hand4 ,to look upon a replica of the work of an artist is like reading a sermon or an oration from a printed page4 ,one may gather much of the teaching but the personal note1 the tone and gesture1 must be lost4 ,but there are many who can gather the words of great men only from books4 ,there are1 moreover1 books which have never been spoken and wherein alone the message is to be found4 ,in like manner there are works1 emanating from the hand of great designers which can only be made available for the many in a form of reproduction4 ,the wall paper cited as an illustration is of this class4 ,were it not for the printing press this beautiful design could not have passed beyond the studio1 and while it is a great thing if a wealthy man can commission a ,whistler to decorate a peacock room1 it is an advantage by no means to be ignored that a well designed wall paper can be purchased by the piece4 ,but while this is true of such of the household goods as cannot be procured except by the medium of the machine1 there are other examples4 ,in the case of the wall paper the function of the machine is simply to transfer the proper design to the paper itself4 ,this has no identity except as a surface4 ,it is no more to be considered than is a canvas upon which a picture is painted4 ,but when a chair or a table is formed out of pieces of lumber uniformly shaped by one machine1 the seat or top put together by another and the legs or back carved or stamped by a third1 art or individuality is lost because mechanical construction is involved4 ,still more is this the case in the product of the manufactory of pottery4 ,in commercial practice not only is a shape designed without regard to decoration but the same decoration is placed upon several forms1 or a single form is made to suffer as the vehicle for many decorations4 ,some of the results may be pleasing1 even beautiful1 but it is more by luck than guidance and no piece produced in this way has any claim to be classed as a work of art4 ,on the other hand it may happen that a work of art1 in the sense of individual expression1 may not even be beautiful and one is tempted to ask the reason4 ,if a work which is a genuine expression of a man's personality fail to please the senses of those who are trained in the finer perceptions there must be something wrong4 ,if the adverse opinion be at all general amongst the critics it may be assumed that they are right and that the worker is wrong4 ,for example1 the form of a flower is not a fit receptacle for a candle4 ,it often happens that a designer1 struck with the beauty of1 say1 a tulip1 has modeled the flower in clay and made it into a candlestick4 ,now it is obvious that the more closely the model simulates the flower the less appropriate it is for such a purpose4 ,if the model be heavy enough to be of use it must be far removed from its prototype4 ,if a conventional design for a candlestick be adopted the petals of a flower may be shown in relief upon it but there must always be a solid foundation to account for the possibility of use4 ,a favorite form with some designers is a bird's nest made into a flower holder4 ,in this the same criticism applies4 ,a bird's nest is always built to let water escape4 ,even a mud-lined nest is not impervious and the idea is obviously inappropriate4 ,it is important that imitation be avoided and especially the imitation of material4 ,one often hears the remark ,how beautiful1 it looks just like bronze4 ,this1 of course1 comes from the casual observer to whom the skill of the imitation appeals but it cannot be too strongly insisted upon that to imitate one material in another is false from every point of view4 ,nor is it necessary4 ,clay is sufficient in itself4 ,there are so many effects possible in pottery which are not possible in any other medium that it is entirely superfluous to seek outlandish texture and color4 ,to be sure1 such things are popular but that does not make them sound in principle or true in taste4 ,it should not be a purpose of any craft to make pieces merely as an exhibition of skill4 ,this is done sometimes by such versatile workers as the ,japanese1 but it may be laid down as a law that a production of the nature of a tour-de-force1 an object which simply excites wonder at the skill of the worker1 is undignified and meretricious4 ,it is akin to the work of certain painters who delight in painting marble or velvet so as to exhibit a perfect texture only and is but one degree removed from the skill of the pavement artist who with colored chalk draws a lamb chop or a banana in such a manner that the real article seems to be lying on the ground at his feet4 ,the true artist1 be he potter or painter1 works primarily for his own satisfaction4 ,it sometimes happens that a defect1 not large enough to be obvious1 is a temptation to concealment4 ,the public will never know4 ,but the consciousness of the existence of such a blemish will destroy the pride of achievement which should accompany every finished piece4 ,if the worker aims to draw any expression of opinion from the untrained observer it should be in the nature of a remark on how easy the work looks4 ,art will always conceal effort4 ,just as the poet or orator is at his best when he clothes sublime thought in simple words so the artist or craftsman glorifies his vocation when he makes use of means which appear to be within the reach of every observer4 ,in addition to the work of the producer there must be considered the function of the critic4 ,artists are commonly impatient of criticism4 ,tennyson voiced this sentiment when he wrote of ,irresponsible indolent reviewers1 but the power of the critic is rarer than the skill of the craftsman4 ,true1 there are critics and critics4 ,there is the man who knows what he likes and who cannot be persuaded that he likes what is false1 and there is the trained critic who sees with an educated eye and dissects with an unerring word4 ,it is not common to find critic and craftsman in one and the same person and it not infrequently happens that the persons exercising these functions are at variance with each other4 ,but if the critic be correct why is the craftsman wrong8 ,in this let it be presumed that there is nothing wrong with his craft as such2 that he handles his tools skilfully and has perfect control over his material4 ,more than this1 however1 is necessary4 ,the first requirement is a sense of form1 a term which includes outline1 proportion and structure4 ,often and often it is found that a designer depends upon novelty alone for acceptance4 ,he is not altogether to blame in this for the great ,american public will1 more often than not1 ask1 ,is it new8 ,novelty in itself is no claim to consideration2 in fact1 on being shown some product of which it is said ,nothing like it has ever been seen before1 the temptation is great to respond1 ,may its like never be seen again4 ,novelty apart1 form must possess proportion1 balance and grace4 ,a chair must invite the sitter1 a vase must stand securely1 a carpet must lie flat4 ,the absence of these things may evidence an individuality on the part of the designer but it is art at the expense of truth4 ,the second necessary condition is fitness which again is expressed in several ways4 ,a porcelain vase is required to be light1 graceful and refined4 ,a piece of ruder pottery may be no less satisfactory if it exhibit vigor1 strength and solidity4 ,a large pot for a growing tree is1 for these reasons1 more appropriate in grs than in porcelain4 ,porcelain is translucent but such a quality is of no advantage in the case of a flower pot2 the strength of a massive body is1 however1 demanded by the circumstances of use and hence the unfitness of the one and the fitness of the other4 ,another point of fitness is concerned in the correspondence between size1 form and weight4 ,it often happens that one takes hold of a piece of pottery and experiences a shock4 ,the mind unconsciously forms an estimate of what the weight will be but the piece does not respond4 ,the effort put forth in accordance with the appearance of the object either lifts it suddenly into the air or fails to raise it from the table4 ,the artist critic takes note of these things4 ,to handle his wares is a constant pleasure1 for one is not continually disappointed by unexpected violences4 ,this correspondence or equilibrium is apart from the use of a piece of pottery4 ,it is quite as legitimate to express one's ideas in clay in the presentation of simple beauty as it is to express them with paint upon canvas4 ,at the same time there is always a satisfaction in a vase or flower pot that it can be used if required4 ,thus a vase which will not hold water is technically imperfect and the bte noire of the conscientious potter4 ,it is in the harmony of these things that the rle of the critic is seen to advantage4 ,if the artist be capable of criticizing his own work he is in a position to command attention but he must either discipline himself or be disciplined by others1 which1 after all1 is the way of the world at large4 ,,chapter ,,ii3 ,,potter ,it must always be an open question how much credit for artistic feeling can be given to primitive races4 ,the production of pottery was1 at first1 the supplying of a need4 ,clay offered a medium for the making of household utensils which were at once fireproof and impervious4 ,the work does not belong strictly to the earliest stages of civilization but is a development of advancing refinement4,a ,a ,those who wish to study ,indian pottery in detail are referred to ,dr4 ,w4 ,h4 ,holmes' work on the ,aboriginal ,pottery of the ,eastern ,united ,states1 published by the ,smithsonian ,institution1 ,washington1 ,d4 ,c4 ,crude and unprepared clays were used for the most part but the makers could scarcely have been conscious of the charming color-play produced by the burning of a red clay in a smoky fire4 ,the pottery of the ,indians is artistic in the sense of being an expression of an indigenous art and much of it is beautiful1 though whether the makers possessed any real appreciation of beauty is open to doubt4 ,the pottery was exclusively the work of the women4 ,no wheel was employed but the ware was mainly constructed by coiling4 ,long strips of clay were rolled under the hands and made of uniform size and these were then coiled in spiral form1 the rolls being welded together with water4 ,after proceeding a certain height the walls of the growing jar would become weak under their own weight4 ,the piece would then be set aside to undergo a partial hardening upon which the work would be carried forward another stage4 ,the shape being completed and partially dried1 the maker would work over the whole surface with stones or simple tools until the marks of the coils had disappeared and the walls had reached a sufficient thinness4 ,a great deal of skill was exercised in accomplishing this4 ,many of the ,indian forms are transitional4 ,the basket1 the gourd and the bark-made jar suggested their shapes to the potter2 indeed it is sometimes evident that clay vessels were constructed as linings to wicker forms1 the outer layer of twigs being afterwards burned off4 ,the firing was performed in the open flame without any protection1 a fact which accounts for the great irregularity found in quality and color4 ,the decorations used by the ,indian women were of the type common to unglazed wares4 ,the clay was incised or embossed and natural earths were used as pigments4 ,this accounts in great measure for the fitness which may be observed in aboriginal decoration4 ,there is an absence of artificial coloring1 nor is there any straining after effect1 but instead there is shown a sober strength and a sane expression of values which would do credit to a modern designer4 ,america is fortunate in possessing abundant relics of primitive times but it cannot be doubted that in other lands similar work was done1 making allowance1 of course1 for the characteristic variations in national traits4 ,the potter's craft is of such a nature1 using an omnipresent material and requiring the minimum of tools1 that almost every nation on the globe has practiced it4 ,in some it has never been developed beyond the narrow limits of the stone age1 in others it has reached the utmost perfection of cultured skill4 ,for perfection of quality in crude pottery1 no ware has ever surpassed that of ,greece4 ,it is not practicable here to deal with the numerous branches and sub-branches of ,greek pottery2 let it suffice for the present purpose to speak of only two main groups4 ,in the first1 the background of the decoration was supplied by the tint of the bare clay2 in the second1 this tint afforded the color of the decoration itself1 the background being covered with a black pigment4 ,to speak briefly these groups are known as black-figured and red-figured wares4 ,the wheel was early adopted by the ,grecian potters as a means of producing form and although molds were sometimes used1 the wheel was1 to all intents and purposes1 the sole method of manufacture4 ,greek pottery is once fired4 ,birch classes it as glazed terra cotta1 but the glaze is nothing more than the black pigment with which the decoration is carried out4 ,the uncolored part of the clay is not glazed but polished with a hard tool4 ,probably some famous potters employed assistants either to make the pieces or to decorate but it does not appear that there was any reproduction1 at least1 during the best period4 ,at first primitive ideas prevailed4 ,geometric designs were succeeded by rhythmic friezes of beasts and birds done in black4 ,when the human figure made its appearance the faces were all in profile with full-fronting eye while the prominent details of feature and drapery were scratched with a sharp point before burning4 ,the change of method to red on black gave much wider scope for the treatment of the human figure1 rendered a fuller expression possible and enlarged the power of pictorial action4 ,great skill in drawing was manifested and details of both drapery and features were expressed with great care by means of the brush4 ,such was the state of the art when the decadence set in and the work fell into the hands of plagiarists and charlatans4 ,meretricious coloring and gaudy ornament succeeded the refinement and restraint of the earlier days and so the art perished4 ,to the inventive power of the ,romans the ceramic art owes more than one novelty4 ,it would appear that the desideratum of the early days was a black ware4 ,homer in his hymn wrote3 ,pay me my price1 potters1 and ,i will sing4 ,attend1 ,o ,pallas1 and with lifted arm protect their ovens1 ,let all their cups and sacred vessels blacken well ,and baked with good success yield them ,both fair renown and profit4 ,the ,greeks accomplished this blackening by means of a pigment1 the ,romans secured a similar result by a manipulation of the fire4 ,it is well known that the oxide of iron which imparts to the clay a red color will1 if burned in what is known as a reducing fire1 turn black4 ,this is accomplished by keeping the air supply at the lowest possible point and the effect is heightened by the smoke which is partly absorbed by the clay4 ,this black ware is known as ,upchurch pottery from the name of a locality in ,england where large quantities have been found1 but numerous examples occur in ,germany and1 indeed1 wherever the ,roman hosts encamped4 ,a second type of pottery is called ,castor ware and consists of a dark clay upon which the decoration is traced in clay of a lighter color4 ,the decoration was applied as a slip or cream and hence was the forerunner of the modern slip painting or pte-sur-pte4 ,this ware is well worth a study4 ,the decorations consisted largely of conventional borders and panels but it is specially notable on account of the free use of motives drawn from daily life4 ,one of the commonest scenes depicted is the hunt of hare or stag1 the animals and trees being often woven into an almost conventional frieze4 ,the most valued type of ,roman pottery seems to have been the ,aretine or ,samian ware4 ,this is a bright red color and possesses an extremely thin glaze4 ,a particular clay was evidently used1 but all knowledge of its source has been lost4 ,with the importation of ,chinese porcelain by the ,dutch the whole trend of pottery manufacture was changed4 ,no longer was black a desirable color1 white was seen to be much more delicate and beautiful and henceforth the endeavor of the potter was to produce a ware which should be as nearly like porcelain as possible4 ,the crudeness of the clay kept this ideal from being realized1 but various expedients were adopted and gradually better results were obtained4 ,throughout the ,east a type of white pottery was made which1 though stimulated by the ,chinese example1 may have been a relic of the knowledge of the ,egyptians4 ,a crude clay was coated with a white preparation1 possibly ground quartz1 and upon this there were painted conventional designs in sombre colors4 ,a clear glaze covered the whole and imparted to the colors a beautiful quality as of pebbles under water4 ,the nature of the glaze is made evident by the hues assumed by the metallic oxides employed as colorants4 ,copper oxide affords a turquoise blue1 manganese1 a wine purple1 and iron1 a brick red4 ,if the glaze had contained any considerable amount of lead oxide1 these colors would have been quite different2 copper would have produced green1 manganese1 dark brown1 and iron1 yellowish brown4 ,the iron pigment was evidently a clay1 sometimes spoken of as ,armenian bole4 ,the red color is always in raised masses because if a thin wash had been used the color would have yielded to the action of the glaze4 ,this ware1 commonly called ,oriental engobe ware1 affords a fruitful study4 ,effects similar in character were produced by the late ,theodore ,deck of ,paris1 but no considerable use of the ancient methods has ever been attempted4 ,the use of tin and lead in glazing was known to the ,arabian and ,moorish potters but these ingredients were not abundant in the ,east4 ,when1 however1 the ,moorish hosts conquered a part of ,spain in the twelfth century it was found that both lead and tin were available4 ,the result was the development of the enameled ware known by the generic name ,maiolica4 ,some have maintained that this was first made in ,italy but the name is derived from the island of ,maiorca from which much of the pottery was exported4 ,the famous ,alhambra vase remains as a monument to the skill of the ,hispano-,moresque craftsmen1 but it was the ,italian artists of the ,renaissance who brought the enameled wares to perfection4 ,the interest here is artistic and technical rather than historical1 but no one can study the work of the period without learning something of ,luca della ,robbia and ,giorgio ,andreoli1 of ,gubbio and ,pesaro and ,castel ,durante4 ,the use of lead in the glaze proved seductive4 ,it simplified the technical problems and provided a brilliant surface but alas6 the colors suffered and one by one they succumbed4 ,the blue of cobalt1 however1 proved indestructible and so1 when the technical knowledge of the ,south met the traditions borrowed from the ,chinese1 there was born1 in the little town of ,delft in ,holland1 the blue enameled ware which has ever since been known by the name of its native place4 ,as to the technical details of the production of ,delft ware a great deal of information is available4 ,the clay used contained a goodly proportion of lime and this served to hold the enamel in perfect union with the body4 ,the decoration was painted in cobalt blue upon the unburned surface of the enamel4 ,this was1 in a measure1 courting a difficulty but it is the glory of the craft that a difficulty is cheerfully accepted if in the overcoming there is found success4 ,if the ,delft potters had burned their enamel in order to make the painting easy1 the world would never have enjoyed the tender tone of blue for which this pottery is famous4 ,by painting the blue color over the powdery enamel1 a more perfect union of enamel and color was accomplished than would have been possible by any other means4 ,this fact alone is sufficient to account for the unsatisfactory nature of the modern1 so-called1 ,delft4 ,difficulties have been avoided rather than met and the success of the early masters has eluded their recent followers4 ,much of the pottery made in ,france in the seventeenth century was inspired by the ,italian renaissance4 ,in fact the word faience is due to the avowed intention of the manufacturers of ,nevers to copy the enameled pottery of ,faenza4 ,almost the only novelty of the time was the inversion1 by the ,nevers potters1 of the ,delft idea4 ,instead of a white enamel with a blue decoration they used1 in part1 a blue ground with a decoration in white4 ,it is not known that this variation found acceptance in any other place but in many localities1 notably at ,rouen1 the manufacture of enameled wares was pursued with great success4 ,the only real difference between the wares of ,spain1 ,italy and ,france1 lies in the decorative treatment4 ,sometimes the emphasis was laid upon lustres1 sometimes on blue and white and again upon polychrome painting4 ,in one place there was an extensive use made of pictorial treatment1 in another all was conventional4 ,the differences are interesting to a student or a collector but to the craftsman enameled pottery affords but one1 though by no means an unimportant1 means of expression4 ,france1 however1 gave birth to two important and interesting departures from the beaten track2 the so-called ,henri deux ware1 and the faience of ,bernard ,palissy4 ,important as these are to the ceramist1 it is a remarkable fact that neither of them had any appreciable influence upon the art as a whole nor did they leave any descendants4 ,a good deal of controversy has raged around the pottery commonly known as ,henri ,,ii1 some authorities claiming that it should be called ,faience d',oiron1 and others assigning to it the name ,saint ,porchaire4 ,it was1 quite evidently1 the production of an individual or group of individuals who had no connection with ordinary pottery manufacture1 and the small quantity produced is evidence that it was made for personal pleasure4 ,the name ,henri ,,ii is undoubtedly satisfactory1 for it was made in the reign of the second ,henry and some pieces bear the monogram of the king4 ,on the other hand ,h may be the initial of ,helene d',hengest1 who occupied the chateau d',oiron and who had in her employ one ,bernard who filled the position of librarian4 ,the style of the work seems to indicate a devotion to books1 for the patterns are suggestive of book-binding tool work but were not produced in the same way4 ,the ware was made of a natural cream-colored clay and the shapes were modeled with great skill4 ,upon the plain surface patterns were tooled or incised and the hollows thus formed were filled in with dark-colored clays4 ,the whole was then covered with a clear lead glaze which afforded a finish very much like modern earthenware4 ,the origin of this work is a matter of little more than academic interest but the technical details are of such importance as to be well worth a study4 ,the ware is original and unique4 ,no pottery either before or since has approached it in method1 and the quality of most of the pieces is all that could be desired4 ,such was the elaboration of detail that no price could have been set upon the ware and it was evidently not made for sale4 ,a distinct growth in style can be traced4 ,the first pieces were somewhat archaic and even crude but as skill was acquired greater perfection was attained4 ,as is too often the case1 however1 the skillful hand overreached itself and the later pieces are loaded with meretricious detail in many colors4 ,there are only about fifty pieces known and these are equally divided between the museums of ,france and ,england4 ,bernard ,palissy was a versatile genius but is here only considered as a potter4 ,he states in his records that he was inspired by seeing an enameled cup4 ,it was at one time supposed that this cup was of ,italian maiolica but later authorities incline to the belief that it was a piece of ,chinese porcelain which ,palissy supposed to have been enameled4 ,no white clay was known to him but enameled wares were quite accessible4 ,it can scarcely be believed that maiolica was a novelty but it can easily be understood that a piece of white porcelain1 viewed in the light of the contemporary knowledge of enamels1 would appear of marvellous quality4 ,palissy essayed to imitate this wonder but attacked the problem from the standpoint of an opaque glaze4 ,he spent fifteen years in experimenting but never realized his ideal4 ,he did1 however1 produce a palette of marvellous colored enamels4 ,he was a close student of nature and modeled all kinds of natural objects1 glazing them in the proper hues4 ,he also designed and made vases and service pieces1 some with figure embossments4 ,the story of his struggles is readily accessible to any who are interested4 ,palissy left little or no impression upon the ceramic art of his time but in recent years some work has been done in colored glazes fusible at a low temperature4 ,this ware is sometimes sold under the name of maiolica but it is more nearly an imitation of ,palissy4 ,the main difference between the two types is that while the maiolica or tin-glazed pottery of ,spain1 ,italy and ,france consisted for the most part of a white enameled surface upon which painting was applied1 ,palissy used little or no white enamel but decorated his wares with tinted glazes which themselves supplied the colors4 ,in the low countries and the ,german states there was made the striking and original pottery known as ,grs de ,flandres4 ,the clay was of the type commonly used for the manufacture of stone-ware and appears in three colors1 brown1 gray and cream4 ,the ware was made on the wheel and embossments more or less elaborate were subsequently added4 ,the unique feature consisted in the method of applying the glaze4 ,this was simply common salt1 thrown into the heated kiln and volatilized4 ,the salt vapor bathed the glowing pottery and combined with its substance1 thus producing the delightful orange-skin texture known as salt glaze4 ,the knowledge of this method was conveyed to ,england in the seventeenth century and gained wide acceptance there4 ,the ,english potters preferred to use clays which were almost white1 and after glazing a decoration in brilliant colors was sometimes added4 ,naturalistic treatment was not attempted but conventionalized subjects were used with almost the effect of jewelry4 ,the temperature at which this work can be produced varies with the clay4 ,many fusible clays will take a salt glaze but the beauty of the product depends to a large extent upon the purity of the body4 ,this necessitates a hard fire1 for white-burning clays always need a high temperature for vitrification4 ,the early potteries of ,england were dependent largely upon clay effects4 ,some little enameled ware was made and is known as ,english ,delft2 but the bulk of the work was slip painted1 incised1 marbled or embossed4 ,each of these methods is capable of an intelligent application and all are within the reach of the artist potter4 ,,chapter ,,iii3 ,,porcelain ,the production of porcelain is the goal of the potter4 ,the pure white of the clay and the possibility of unlimited fire treatment exert a profound influence upon the imagination while the difficulties of manipulation only serve to stimulate the energy of the enthusiast4 ,for present purposes not much is to be learned from the soft porcelains of ,france nor from the bone china of ,england4 ,german and ,french hard porcelain are but developments of the ,chinese idea and therefore need not be studied apart from their prototype4 ,the earliest date of ,chinese porcelain is unknown4 ,the records of the nation are very ancient but their meaning is often obscured by the fact that in the ,chinese language the same word was used of old to denote both porcelain and earthenware4 ,specimens dating from only the tenth century ,a4 ,d4 look almost incredibly old4 ,they are coarse and heavy in structure but are aglow with vibrant color4 ,the finest porcelains date from the fourteenth and fifteenth centuries and these are the ideals towards which every modern potter looks4 ,broadly it may be stated that two methods prevailed4 ,in the former the glaze itself was charged with color or the coloring matter was applied to the clay beneath the glaze4 ,in the latter the porcelain was finished as to body and glaze and the decoration was applied at a subsequent and much lighter burn4 ,the first named class is called single-colored porcelain2 the second has several names such as the famille rose and famille verte as defined by ,jacquemart4 ,in the single-color class it is evident that the potters were not at all sure of their results4 ,in many museums there are to be found examples of ox-blood red1 more or less fine1 and1 with them1 other pieces which were intended to be red but which failed in the fire4 ,the wonder is1 in these cases1 that the pieces1 even though failures1 are beautiful4 ,the knowledge required for the production of these wares is largely scientific2 at the same time it is not to be believed that the ,chinese had any special scientific training4 ,they evidently traveled a long and tortuous path before the goal was reached1 in fact1 they often fell short of it altogether1 but they had plenty of time and unlimited patience4 ,the modern potter is1 if less patient1 more fortunate in that the course has been marked out with more or less accuracy and1 if the landmarks of science be heeded1 a certain degree of success may be attained4 ,this single-color work is the true field of the ceramist4 ,anyone possessing the power of using a pencil1 and with a large stock of patience1 may produce over-glaze decoration1 but to prepare glazes of many hues and to consign them unprotected to the fury of the furnace1 requires skill1 patience1 courage and enthusiasm4 ,during the last twenty years a new school has arisen which combines in a measure the advantages of the two ,chinese methods4 ,colors are prepared from refractory materials and upon clay or soft burned biscuit ware1 scenes1 in more or less conventional form1 are painted1 or else a design purely conventional in character is applied by the artist4 ,the ware is then glazed and subjected to the severe fire which all porcelain undergoes4 ,the result is that the porcelain and the painting are united in a sense that can never be the case with over-glaze treatment4 ,the colors become part of a purely ceramic unit2 the spirit of the artist is fixed by the fire4 ,to this class belong the porcelain of ,copenhagen and the recent product of ,sevres4 ,these1 of course1 represent the result of much arduous training and many tedious experiments4 ,both the training and the experiments are necessary to some extent for every worker1 not only because pottery clays vary much in composition1 but because individuality can only be obtained by the preparation1 in the laboratory1 of the desired compounds4 ,the ,chinese1 doubtless1 stumbled upon many of their successes by accident1 helped by the fact that the character of the fire employed influenced many of their colors4 ,this will be explained in a later chapter4 ,they were1 however1 quick to seize upon that which was good4 ,many fanciful names were given to the rarest colors1 such as the violet of wild apples1 liquid dawn and the red of the bean blossom4 ,this idea has been carried further in ,france by the invention of such names as ,sang-de-boeuf1 ,sang-de-poulet1 clair-de-lune1 etc41 and pursued in this country in ,peach blow4 ,in the over-glaze treatment1 the type named famille verte is characterized by a clear green glaze or enamel over a design in black4 ,the whole is painted over the porcelain glaze and the green enamel is so soft that it is often decomposed on the surface4 ,when a broad black mass is covered with green the decomposition gives rise to prismatic colors and occasions the term raven's wing black4 ,some of this ware has also been gilt but the gold lines have disappeared and can only be located by the slight dullness of the enamel where they once were4 ,well known to collectors also are the rose-back plates4 ,these belong to the famille rose in which the characteristic note is a delicate rose pink4 ,this color is prepared from gold and when it is placed upon the back of an egg-shell plate a tender rosy transparency is imparted to the piece4 ,one of the best known of the single colors is the pale sea green named celadon by the ,french4 ,this color in ,china was called the sky after rain and was considered both rare and valuable4 ,the porcelain of ,copenhagen is the product of scientific skill and artistic taste4 ,in the studios attached to the ,royal ,manufactory there has grown up a tradition of work and criticism which is fostered by ladies of birth and position4 ,many of these paint upon the porcelain themselves and so constitute a school which has become world famous4 ,natural objects are1 for the most part1 chosen and1 as the palette of colors is1 owing to the intense fire1 quite limited and low in key1 a tone of quiet atmosphere pervades the painting4 ,this is accentuated by the use of the air-brush to distribute a ground color upon the ware in graduated strength4 ,at the ,national ,manufactory of ,sevres there has been some attempt to follow the ,copenhagen method but to a greater extent the work is along the lines of conventionalized form4 ,in this treatment the ,french artists excel1 being wonderfully accurate--almost too accurate--in their lines and spacing4 ,several individual workers in ,france have also pursued this plan1 designing and executing the pieces which have made the ,french artist-potters famous4 ,in the porcelains of ,berlin the quality lies largely in the complete mastery of technical details4 ,the work is1 as would be expected1 ,german in style1 but the paste is pure and the colors are well prepared4 ,from this brief review it will be seen that the interest in the manufacture of porcelain lies not so much in variety as in the value of individual results4 ,in the pottery described in the previous chapter a great many different clays were used and each one proved suggestive to the potter4 ,in porcelain1 on the other hand1 the body clay is almost identical wherever prepared1 the requirement of a white translucent paste being paramount4 ,,chapter ,,iv3 ,,the ,,nature ,,and ,,properties ,,of ,,clay ,clay differs from earth or soil in that it possesses certain characteristics which these do not possess4 ,its distribution is very wide but for the most part it lies concealed from view4 ,in certain parts of the country it is so abundant that it breaks through the surface or is exposed as an outcrop but usually it is covered by the soil which supports vegetation4 ,unless the subsoil consists of sand it is easy to expose a clay by plowing or digging with a spade4 ,it usually appears as a greenish or bluish substance of close and uniform structure4 ,the texture is sometimes smooth but more often numerous small stones are found imbedded in the mass4 ,such clays as are commonly found can be used for the manufacture of some kind of pottery but in the great majority of cases the ware will be red when fired because the clay contains a proportion of oxide of iron4 ,a pure clay does not contain this and therefore becomes white or nearly white in the kiln4 ,pure clay1 known as clay base or clay substance forms a part of all natural clays though sometimes only a small part4 ,it consists of silica1 alumina and water in a state of combination and is thus known as a hydrous aluminium silicate4 ,while this substance is very common as an ingredient of ordinary clay1 it is rarely found alone or uncontaminated4 ,commercial or workable clays may be said to consist of clay base and sand1 with or without other impurities such as lime and oxide of iron4 ,for working purposes it may be granted that the potter has to deal with a mixture of clay and sand4 ,but sand is not a definite expression4 ,it may vary both physically and chemically within wide limits4 ,the physical nature has to do with condition1 the chemical with composition4 ,thus a sand may be almost as coarse as gravel or as fine as the clay itself4 ,it may be a pure quartz sand or it may be a crushed rock of almost any composition4 ,the former is known as quartz1 the latter as feldspar or feldspathic sand because it approaches in composition the group of minerals known as feldspars4 ,each of these ingredients1 clay1 quartz and feldspar1 has an important part to play in the transformation of clay into pottery4 ,few of the clays used in making white pottery possess these ingredients in the correct proportions so that it becomes necessary to make a mixture in which the necessary proportions will be found4 ,for successful pottery making three properties are demanded in a clay4 ,first1 plasticity4 ,without this1 clay could not be shaped at all4 ,it constitutes the obedience of a clay to the forming influence whether hand or mold4 ,the necessity for this quality may be illustrated by the proverb ,making ropes of sand as an example of the impossible4 ,sand1 possessing no plasticity1 cannot be shaped or made to hold together4 ,the second property is porosity4 ,a clay which exhibits a high degree of plasticity can be easily shaped but it cannot be safely dried4 ,the water of plasticity cannot escape and therefore the clay warps and cracks4 ,the function of porosity is to prevent this4 ,a porous clay permits the water to escape freely and the clay can be dried without damage4 ,this condition is produced by the admixture of sand or by the presence of sand in a natural clay4 ,a coarse sand is more effective than a fine sand but a sand that is too coarse will interfere with delicate working while a sand that is too fine approximates the action of the clay itself and produces a substance which is dense rather than porous4 ,porosity is therefore the reverse of plasticity and these two properties must be adjusted so as to balance each other4 ,the third necessary property is commonly known as vitrification but could be better named densification because complete vitrification is not attained in ordinary clay wares4 ,this property may be defined as that which causes a clay to yield to the action of a high temperature so that the result is a ware1 more or less dense1 which is hard1 durable and sonorous4 ,with this there must be coupled a certain amount of resistance to heat treatment so that the pottery does not fuse or collapse during the firing4 ,here also is found the need for adjustment4 ,the clay must yield to the fire but not completely4 ,it must resist but not entirely4 ,plasticity is due to the clay base4 ,not only to its quantity but to its quality also4 ,some forms of clay in which clay base predominates are not plastic because the clay base itself is coarse grained4 ,other forms with less clay base present are plastic because this ingredient is fine grained and tough4 ,pure clay base is also highly resistant to fire and therefore contributes to the refractoriness of the mass4 ,porosity is caused by the sand in the clay4 ,any kind of sand will produce porosity but the effect differs with the condition of the sand4 ,coarse sand is more effective than fine sand4 ,more sand will1 of course1 cause greater porosity4 ,vitrification or densification is due to the feldspar or fusible sand4 ,this also varies with the condition4 ,a fine-grained feldspar will produce vitrification more easily than the same amount of coarse feldspar4 ,certain substances are available for use in pottery mixtures1 which possess one or other of the necessary properties in high degree so that they will impart these properties to a mass to which they are added4 ,kaolin or china clay is usually fine1 white1 and refractory4 ,some kaolins are rather plastic but most of them are short in working and rather tender4 ,for the production of a white ware kaolin is indispensable4 ,no other ingredient will afford the pure white color which is sought after in porcelain and china4 ,ball clay is very plastic1 easily vitrified1 but is not white4 ,the color varies from a cream to a gray4 ,the use of a ball clay is therefore limited in white wares because it will spoil the color4 ,for wares in which a light cream color is not objectionable ball clays are valuable and almost indispensable4 ,stoneware clay is usually a rather plastic clay which contains a good deal of sand1 hence stoneware clays can be used for certain classes of ware without admixture4 ,a rather high temperature is required for most of these clays1 though occasionally one can be found which will become dense at the fire of a studio kiln4 ,the clays sold by the ,enfield ,pottery ,company and by the ,western ,stoneware ,company are of this type4 ,ground flint is a necessary ingredient in almost all pottery4 ,it aids in the porosity of the clay and enables the mixture to be adjusted to fit a special glaze4 ,ground feldspar is also necessary4 ,like flint it aids in the porosity of the unburned clay but unlike flint it produces density in the firing4 ,by a proper adjustment of these ingredients a clay can be composed which will meet the special requirements of the worker4 ,in order to ascertain the properties of any given clay certain simple tests may be made and every clay-worker should know how to do this because one cannot be too well informed as to the materials to be used4 ,first1 water of plasticity4 ,a certain portion of the clay1 dried and powdered1 is weighed out4 ,it is convenient to weigh in grams and to measure in cubic centimeters because in this way calculation is easy4 ,the scales and weights are described in the chapter on glazes4 ,for measuring the water a glass vessel called a graduate is used4 ,one holding a hundred cubic centimeters and graduated in centimeters and tenths can be obtained from a dealer in chemical supplies4 ,one hundred grams of clay is weighed out and transferred to a glass slab4 ,the graduate is filled with water to the one hundred mark4 ,some of this water is then poured on to the clay1 adding little by little as needed until the whole can be worked into a stiff mass of the proper plasticity4 ,the quantity of water used is then carefully noted by observing how much is left in the graduate4 ,suppose1 for instance1 #gj cubic centimeters are found remaining1 the hundred grams of clay has absorbed thirty c4c4 of water and as one c4c4 of water weighs one gram the clay has taken just #cj per cent4 ,this amount is important because it is one of the best indications of plasticity4 ,a very plastic clay may need #dj per cent1 a non-plastic clay may be satisfied with #be per cent4 ,second1 shrinkage4 ,the mass of plastic clay is now transferred to a plaster bat and rolled or pressed out into a smooth slab about #ab centimeters long4 ,here again the centimeter is used in preference to the inch as being more easily calculated4 ,a faint line is ruled on the clay slab and two fine scratches are marked exactly ten centimeters apart4 ,the edges are trimmed and the excess clay made up into three or four small pieces which are to be fired in different parts of the kiln as tests for density4 ,when the clay slab is dry the distance between the marks is measured and noted4 ,the ten centimeters being divided into one hundred millimeters1 each millimeter of shrinkage means one per cent4 ,after firing1 a second measurement is made and the differences are noted as dry shrinkage and fire shrinkage respectively4 ,third1 firing4 ,the slab with the measurement upon it is set in the kiln in the place where the clay wares are to receive the first or biscuit fire and the small pieces are arranged in different places so as to secure as many different conditions as possible4 ,the position of each should be carefully recorded4 ,after firing1 the marks on the slab are measured as already described and note is taken of any warping of the piece4 ,the color is also recorded4 ,the small pieces should be tested for porosity or absorption of water but this is rather a delicate operation and needs a particularly sensitive balance4 ,generally it will suffice to use a wet sponge or to dip each piece into water1 removing it quickly and noting carefully the rate of speed at which the water is absorbed4 ,if the water should be scarcely absorbed at all a line of ink may be drawn upon the pottery with a pen1 the piece being perfectly dry4 ,in a fully vitrified ware the ink can be washed off1 leaving scarcely a mark but the test is quite sensitive and with a little practice will afford an excellent means of comparing the density of different clays or of the same clay at different temperatures4 ,fourth1 glazing4 ,it is well to have ready a small supply of a standard clear glaze4 ,each of the test pieces should be covered with this in a rather thin coat and then they should all be fired again1 this time close together so that they will receive the same heat treatment4 ,this will enable one to determine what degree of fire for the clay will best suit the glaze4 ,,chapter ,v3 ,,the ,,preparation ,,of ,,the ,,clay ,a clay having been selected in accordance with the tests described1 it becomes necessary to prepare it for use4 ,a fairly large supply should be obtained and stored in a dry place4 ,most natural clays need some kind of cleansing for there are almost always foreign substances present4 ,this cleansing is accomplished by reducing the clay to the fluid known as slip4 ,the necessary appliances for making slip are as follows3 ,a large sieve of quarter-inch mesh4 ,a small wire sieve of about #ad meshes to the inch4 ,a large barrel4 ,two galvanized pails4 ,the clay is1 after drying1 powdered and sifted through the large sieve4 ,one of the pails is half filled with clean water and the clay1 handful by handful1 is sprinkled into it4 ,the clay rapidly absorbs the water and sinks to the bottom4 ,the addition of clay is continued until a small mound rises through the water1 when the whole is left to soak for an hour4 ,the bared arm is then plunged into the pail and the mass stirred vigorously4 ,a stick or paddle will serve1 of course1 but the potter learns a great deal by the feel of the clay and therefore the hand is best4 ,it is said that he is a poor sailor who will not dip his hands in the tar bucket and in like manner1 he is a poor potter who fears the slip tub4 ,this stirring will tell a good deal about the probable working of the clay4 ,it may be stony or sandy or greasy4 ,the large stones and roots will have been removed by the sieve but now1 after thorough mixing1 the slip is poured through the small sieve into the barrel4 ,both pails may be kept going at once1 one being filled while the other is soaking and so on until the barrel is full or1 at least1 a good quantity of slip has been prepared4 ,if the clay prove very sandy it should be washed4 ,the mixture in the pail having been well stirred is allowed to stand for a definite time1 say one minute4 ,the slip is then poured into the second pail and it will be found that a quantity of sand has settled4 ,this is thrown away and the slip in the second pail is examined4 ,if enough sand has been removed1 the slip may be poured into the barrel1 using the fine sieve as already described4 ,if still sandy the process should be repeated1 the settling being for two minutes4 ,experience is the best guide in this operation but all the sand should not be removed4 ,when the barrel is full of slip it is allowed to stand over night when some inches of clear water will be found at the top4 ,this is removed with a siphon which may be made of a piece of lead or rubber pipe4 ,the removal of the water results in the thickening of the slip and the contents of the barrel should be thoroughly stirred with a long wooden paddle to insure a uniform consistency4 ,if the slip is found to be still thin another settling and removal of the water will thicken it4 ,the slip thus prepared will keep indefinitely1 provided that it is not allowed to become dry by evaporation4 ,it improves greatly with age4 ,this is the material which is used for casting as will be described later but for plastic work it must be still further thickened4 ,a shallow box may be procured and made water-tight and the slip1 when poured into it1 will thicken much more rapidly than in the barrel1 but it is better to have some shallow plaster dishes as the plaster itself absorbs the water and thickens the clay4 ,instructions for making these dishes appear in the chapter on plaster4 ,these directions will suffice for the preparation of a natural clay but it is sometimes desired to prepare a white body either of earthenware or porcelain4 ,these bodies do not exist in nature and therefore a mixture must be made4 ,the ingredients are kaolin or white porcelain clay1 ball clay or plastic potters' clay1 ground quartz or flint1 and ground feldspar4,b ,b ,georgia ,kaolin and ,tennessee ,ball ,clay may be procured from the ,john ,h4 ,sant and ,sons ,company1 ,east ,liverpool1 ,ohio1 and flint and feldspar from the ,golding ,sons' ,company1 ,trenton1 ,n4 ,j41 or the ,eureka ,flint and ,spar ,company1 ,trenton1 ,n4 ,j41 in quantities of not less than one barrel or sack4 ,a suitable mixture for earthenware is-- ,georgia ,clay,c #bj parts by weight ,tennessee ,ball ,clay #cj ,flint #ce ,feldspar #ae --- #ajj and for porcelain-- ,georgia ,clay #de parts by weight ,flint #ce ,feldspar #bj --- #ajj ,c ,if ,english china clay can be procured it will make a whiter ware than ,georgia clay4 ,the earthenware will be creamy in color and porous at an ordinary fire4 ,the porcelain will need a hard fire and will be white and translucent4 ,it is1 however1 non-plastic and hard to work4 ,the preparation of these mixtures of course necessitates a pair of scales but otherwise the treatment of the mix is the same as that of natural clay4 ,washing is not necessary but the clay must be powdered1 mixed with the flint and spar1 and sprinkled into water as already described4 ,in place of the wire sieve1 however1 a silk lawn of #abj meshes to the inch should be used4 ,the lawn is simply a fine sieve and is named because of the material 7also called bolting cloth71 with which it is covered4 ,have a carpenter make a box without a bottom4 ,cypress or oak should be used and this should be a full half inch thick4 ,four strips of the same thickness are also to be provided4 ,the box may be of any convenient size2 eight inches square and four inches deep is about right4 ,the sides should be fastened together with brass screws to avoid rust and a piece of lawn is strained tightly across the bottom and secured with copper or brass tacks4 ,a strip of coarse muslin folded and laid along the edges will help to prevent the lawn from tearing1 the tacks being1 of course1 driven through both muslin and lawn4 ,then the four wooden strips are set upon the muslin and secured with brass screws4 ,the completed lawn is then a tray of which the bottom is formed of lawn4 ,the strips of wood beneath serve to protect the lawn when placed on a table as well as to assist in holding it firmly4,d ,d ,silk lawn of any desired mesh may be purchased by the yard from ,a4 ,sartorius ,company1 #eg ,murray ,street1 ,new ,york ,city2 or brass sieves ready for use from the ,w4 ,s4 ,tyler ,company1 ,cleveland1 ,o4 ,for storing clay in the plastic state there is nothing better than stoneware jars4 ,these may be had of any size and a tinman should make close-fitting covers4 ,earthenware covers do not fit tight and are always getting broken4 ,a little water is poured into each jar and a support provided for the clay so that it does not rest in contact with the water4 ,under any conditions clay will slowly harden so that not too large a stock should be kept4 ,slip1 on the other hand1 keeps well so long as some water is always on the top and it is not a long process to stiffen it into clay4 ,,chapter ,,vi3 ,,mold-,,making ,,and ,,plaster ,plaster is almost a necessity to the potter and therefore something should be learned about it4 ,even if one does not use molds there are numberless purposes for which plaster is convenient4 ,for stiffening slip into clay1 and for absorbing water from glazes1 shallow dishes of plaster are used1 and for holding work either in making or drying1 plaster bats or round slabs are always in demand4 ,it is best to purchase the finest quality of potters' plaster by the barrel4,e ,it will keep indefinitely if stored in a dry place4 ,the necessary appliances are3 ,one or two large jugs for mixing1 or a metal can with a spout4 ,a metal spider or frying pan4 ,six feet of rubber machine belting1 six inches wide1 or similar strips cut from linoleum or enameled cloth4 ,two or three thin pieces of steel of various degrees of flexibility 7scrapers74 ,handy knives1 called vegetable knives4 ,a small painter's brush4 ,two or three fine sponges4 ,e ,calvin ,tomkins1 #cj ,church ,street1 ,new ,york ,city4 ,to begin with1 a size of soft soap and water is prepared4 ,put a quart of water into a kettle and add a piece of soap the size of an egg4,f ,simmer for an hour or until the soap is entirely dissolved and then set aside to cool4 ,when cold the size should be of the consistency of maple syrup4 ,this size is used whenever plaster is to be kept from sticking to a form or surface1 and it has also the merit of causing clay to stick to plaster4 ,for example1 if a mold is to be taken from a clay model no size should be used1 but if a plaster form is used as a foundation for clay ornament it should be well sized first4 ,the size is laid on with a brush and wiped off with a sponge4 ,another sponge is then used with clean water and the sized surface is washed1 all superfluous water being removed4 ,size is then applied a second time and washed off as before4 ,a third application is sometimes necessary1 or until the sized surface rejects water like grease does4 ,on the last sizing1 water is not applied1 but the surface is polished with the sponge containing size4 ,if the surface to be prepared be of wood or metal a single coat of size will often suffice1 but if it be of plaster three or four applications are often necessary4 ,f ,any good laundry soap will serve1 but it should be sliced thin4 ,the first lesson may well be the manufacture of a plaster bat4 ,the frying pan is first sized and set upon a level table4 ,let us suppose that a quart of water will fill it to about an inch in depth4 ,this amount of water is put into a jug and two pounds and three-quarters of dry plaster is weighed out and allowed to trickle through the fingers into the water4 ,this proportion has been found to be best for ordinary mixings4 ,a smaller quantity of plaster to the quart of water will result in a very soft bat2 a larger quantity will be proportionately harder4 ,after the plaster has soaked up all the water it will take1 that is in about two minutes' time1 the hand is plunged in and the whole stirred to a smooth cream4 ,all lumps must be broken up and the air bubbles removed as far as possible4 ,continue stirring gently and presently the mixture will be felt to grow thicker4 ,the psychological moment arrives when the plaster forms upon the hand a white coating which cannot be shaken off4 ,the creamy liquid is then poured into the frying pan which is gently shaken to level the surface4 ,if the plaster has been poured at the right moment it will set smoothly with a mat surface like sugar icing4 ,if poured too late it will be stiff and difficult to level1 and if poured too soon it will curdle on the surface and water will be seen above the plaster4 ,a little practice will show the right moment4 ,the jug should be washed out immediately while the plaster is soft4 ,in the place used for plaster work a tub should be provided in which all vessels and tools can be washed1 for1 if allowed to flow down the waste pipe of a sink1 the plaster will speedily choke the outflow4 ,after standing for some ten minutes1 more or less1 the bat in the frying pan will grow warm4 ,this is the sign of a combination between the plaster and the water and shows the completion of the setting4 ,the pan is now taken by the handle and1 holding it upside down1 the edge is rapped smartly on a brick or stone4 ,this will cause the contents to fall out and there is a smooth disc which is one of the most useful of appliances4 ,the edge will need to be scraped and the bat can be set aside until needed4 ,it will be good practice to make a half dozen of these4 ,this process of mixing and pouring plaster is the same for all operations and the instructions will not be repeated1 but when the student is told to pour plaster it will be presumed that this experiment has already been made4 ,illustration3 ,fig4 #a4 ,a1 table4 ,b1 clay mound4 ,c1 plaster4 ,d1 rubber belt4 ,the next step is the making of a plaster bowl or dish for the purpose of drying out slip or glaze4 ,a convenient size should be determined upon as it is best to have all the dishes the same4 ,upon any flat1 smooth surface a mound of clay is reared which shall be the size and depth of the inside of the proposed dish4 ,about twelve inches in diameter and three inches deep is a good size1 though fourteen inches is not too large for the former dimension4 ,this mound should be made as nearly circular as possible and the clay finished as smoothly as may be4 ,the rubber belt is then set around the mound in the form of a hoop leaving a space of two inches between the clay mound and the rubber hoop4 ,the rubber is fastened either by tying with string or by binding the overlapping ends with clothes pins4 ,a roll of soft clay is laid down where the belt joins the table and pressed down outside to prevent leakage4 ,enough plaster to fill the space within the belt is now mixed and poured1 covering the clay mound to a depth of at least one inch4 ,when the plaster has set the rubber is detached1 the whole turned over and the clay dug out4 ,we have now a circular plaster dish three inches deep but we have only one4 ,the trouble of rebuilding the clay is unnecessary a second time because a case or reverse can be made from which as many dishes as may be necessary can be formed4 ,illustration3 ,fig4 #b4 ,c1 plaster dish4 ,d1 rubber belt4 ,e1 plaster case or reverse4 ,illustration3 ,fig4 #c4 ,plaster case1 with rubber belt1 arranged for pouring4 ,the dish is carefully smoothed and trimmed4 ,the sharp edge is removed and the inside is dressed with fine sandpaper to a perfectly smooth surface4 ,size is now applied to the inside and upper edge until a bright slippery surface is obtained4 ,the rubber belt is now bound closely around the dish and plaster is poured to a depth of about one and one-half inches on the edge4 ,this1 of course1 makes a depth of four and one-half inches in the center4 ,when this new plaster has set in turn the rubber is removed and the two castings can be easily separated by inserting a knife at the junction4 ,the knife should be gently driven in with a hammer4 ,obviously it is now possible to make a number of dishes from the reverse thus obtained1 by simply binding the rubber belt around each time and pouring plaster as at first4 ,the original mold having been sized is no longer absorbent but must be kept in case additional reverses are needed4 ,the molds or dishes must be thoroughly dried out before being used4 ,the molding of a vase form is more elaborate but not really difficult4 ,even if one does not intend to produce pottery by molding there is always an advantage in having a number of simple forms upon which to make experiments4 ,the vase to be molded is first drawn to exact size upon paper and a plaster model is turned on a lathe4 ,this can be done equally well on the potters' wheel and the method is as follows3 ,a plaster bat is saturated with water and set upon the wheel so as to run true when the wheel is revolved1 and is cemented to the wheel head by a little slip4 ,a few deep scratches are made on the face of the bat and a cylinder1 either of the rubber belt or of stiff paper1 is rolled up and set on end in the center of the bat4 ,the size of the cylinder should be a little larger every way than the proposed vase4 ,plaster is now mixed and poured to fill the cylinder4 ,it will adhere to the bat below by reason of the scratches4 ,when the plaster has set1 the cylinder is unfastened and removed and the turning may begin4 ,to turn plaster well involves a good deal of practice but it is better to spoil three or four plaster cores in the learning than to spend a long time on one for fear of damaging it4 ,illustration3 ,fig4 #d4 ,turning tools for plaster4 ,illustration3 ,fig4 #e4 ,position of tool in turning4 ,a1 correct4 ,b and ,c1 incorrect4 ,the board support and turning stick described on page #ajj are used in turning plaster as well as clay4 ,the turning stick is held in the left hand and the point is pressed into the board4 ,all this is1 of course1 made ready before the plaster is poured4 ,the turning tools are here illustrated4 ,they are not sold in the stores but can be made by any machinist4 ,the head or cutting blade consists of a flat piece of steel through the center of which is a shaft or pin which is driven into a handle4 ,the head may be of any shape but the triangle and the circle will meet every need4 ,the tool is held in right hand and braced against the turning stick1 the stick and tool being moved together by raising or lowering the left hand which holds the butt of the stick4 ,while the plaster is still soft the round tool is used and the rough form is rapidly turned4 ,then as the setting of the plaster proceeds and it is found to grow harder1 the triangle tool should be used and the shape gradually wrought out with the point4 ,finally by using the circle tool for concave lines and an edge of the triangle tool for convex lines the form is perfected4 ,the surface is to be finished and the tool marks removed by using1 free hand1 a flexible scraper which is bent by the fingers and thumb to fit the lines of the form1 and a final smoothing is given by fine sandpaper1 the wheel being revolved all the time4 ,at the top of the form a small cylindrical piece is left1 called the spare which represents the thickness of the mold substance1 and for the bottom a small piece is turned in the shape of a truncated cone4 ,the small end of this should be the same diameter as the base of the vase4 ,these are shown in the illustration 7,fig4 #f74 ,illustration3 ,fig4 #f4 ,vase with foot piece and template4 ,a1 vase4 ,b1 spare4 ,c1 foot piece4 ,d ,d1 templates4 ,n ,n ,n ,n1 natches4 ,it will be obvious that in the directions given above the base of the vase is not finished off and therefore the form must be cut off from the bat1 either by a knife or saw1 and the base is then finished by hand1 or by setting the form upside down in a clay cradle--called a chum--and turning the base true4 ,the form is now ready for molding4 ,illustration3 ,fig4 #g4 ,end plates for mold4 ,e1 upper plate4 ,e'1 lower plate4 ,n ,n1 natches4 ,the plaster vase is laid upon its side on a piece of soft clay and a thin bat or plaster slab is cut to fit the outline4 ,this template should fit with reasonable accuracy but need not be absolutely exact4 ,a pair of these will be required1 one to fit each side of the form4 ,these slabs or sheets of plaster are always useful and if a sheet of glass is kept handy any excess of plaster left from a mixing may be poured on to it4 ,this upon setting is easily detached and will present a smooth face where it has rested on the glass4 ,the pair of templates must include1 in their outline1 both the spare and the foot piece but should not extend beyond either of these4 ,the outside diameter of the mold is now to be determined and the templates cut to this dimension so that the two together1 with the vase between them1 constitute a longitudinal section of the mold4 ,the vase must now be divided accurately into two halves by a line running from top to bottom4 ,there are several ways of doing this4 ,while the form is still on the bat a diameter of the bat may be drawn and a perpendicular erected from each end of this diameter4 ,these perpendicular lines will1 of course1 mark the center of the vase on each side2 or after the vase has been cut off another method is possible4 ,with a pair of dividers find the center of both the top and the bottom of the vase4 ,mark each with a small hole or the point of a pencil4 ,now lay the vase on its side on the clay cradle upon a glass sheet or other level surface and raise or depress one end until the two centers are exactly the same height from the glass4 ,take this height in the dividers and1 sliding one of the compass legs along the glass1 gently scratch the plaster vase with the other or upper point4 ,if the two centers have been accurately adjusted this scratch line will be the exact center of the form4 ,some soft clay is now built up on each side of the vase and the templates are pressed down upon it1 one on each side until the upper face of each corresponds with the scratched line4 ,the vase is now seen to be buried as to one half in a plaster surface1 and plaster poured on this will give a half mold4 ,there is yet1 however1 nothing to confine the plaster and it would flow away as fast as poured4 ,two end plates are necessary and these must rise in a half circle above the bed formed by the templates4 ,the part below may be of any shape but must be high enough to cause the diameter of the half circle to coincide with the plane of the templates4 ,two pieces of cardboard1 wood1 or rubber belt are now bound to the sides1 the apertures at the top and bottom1 caused by the curve of the end plates1 are stopped with clay and the whole presents the appearance of a vase1 only half of which is visible1 lying in a shallow trough4 ,all the fitting should be carefully done but the tying up is not yet4 ,the whole is now taken apart and well sized4 ,vase1 foot piece1 templates and end pieces are all to be sized thoroughly in the manner described4 ,they are then put together again and bound around with twine4 ,it is necessary now to make provision for the proper fitting of the halves of the mold4 ,this is done by providing knobs and hollows which fit together4 ,these are technically known as natches and will be referred to as such4 ,take two pieces of moderately stiff clay each about the size of a cherry4 ,roll them into neat balls and cut them in two with a thin knife4 ,lay each of the halves1 flat side down1 upon the templates1 two on each1 placing them in pairs opposite to each other4 ,affix two or more of these on the inner face of the bottom end plate4 ,now mix and pour the plaster4 ,this should be poured to the height of the top of the end plates and1 after pouring1 shake this well down by dipping the fingers into it1 so that no bubbles may cling to the surfaces below4 ,as soon as the plaster has become firm but while it is still soft remove the string and the side boards1 pull off the pieces of clay and with a straight1 thin piece of wood scrape off the surplus of plaster by following the line of the end plates and thus making a half cylinder4 ,as soon as the plaster has become warm the whole may be turned over and the templates and end plates removed4 ,the four half spheres of clay will be found embedded in the face of the plaster and these1 being removed1 will leave four hemispherical depressions4 ,the vase can now be gently detached from its bed and the first half of the mold is completed4 ,a little dressing will be necessary4 ,all overhanging edges and rough places should be finished off and the hollow natches smoothed with a piece of muslin on the end of a finger4 ,the second half is simple4 ,replace the vase in the half mold1 set the foot piece in its place1 replace the end plates with the diameter on the line as before but with the semi-circular edges upward1 and set two or three clay natches on the bottom one4 ,size1 bind up1 pour and scrape off as before1 thus completing the two halves of the mold in cylindrical form4 ,it only now remains to make the bottom for1 at present1 the mold is open at both ends4 ,the two halves with the vase inside are bound very tightly together with twine and set on the table bottom upwards4 ,the clay natches in the bottom are taken out and the hollows smoothed4 ,the foot piece is taken out and the rough places dressed4 ,the bottom end of the vase is now visible and this1 together with the end of the mold1 is sized4 ,a strip of stout paper is bound around the mold1 projecting about an inch above the end and plaster is poured to fill it4 ,when this is set the paper is peeled off and the edges of the mold are dressed smooth4 ,the bottom may now be detached by inserting a thin knife at the junction1 the mold opened and the form taken out4 ,the mold is now in three parts which may be put together at will and used for casting the vase in clay4 ,,chapter ,,vii3 ,,cases ,,and ,,working ,,molds ,the mold described in the previous chapter is called1 technically1 a block mold and is not1 as a rule1 used for making the clay ware4 ,the reason for this is that molds will wear out more or less rapidly and to repeat the process of making new ones from the original form would be tedious and expensive4 ,from the block mold a reverse is made1 called a case1 and from this1 in turn1 working molds are made in any required number4 ,while it is possible to use the block mold as a working mold1 and1 if only a few pieces are required this is quite sufficient1 yet1 as it is often necessary to have a number of molds1 the student should understand how to make a case4 ,a case may be defined as a mold from which a mold is made4 ,if one can imagine the visible half of the vase form as it appears in making the mold1 with the templates and ends cemented into one piece1 one has a conception of one half of a case4 ,the problem is to make this with permanent but movable ends so as to have a convenient form from which half molds may be easily made4 ,illustration3 ,fig4 #h4 ,offset plates4 ,f1 top plate1 front view4 ,f'1 side view4 ,g ,g'1 bottom plate4 ,illustration3 ,fig4 #i4 ,sectional view of mold ready for casing4 ,a1 mold4 ,b ,b1 offset plates4 ,c ,c1 end plates4 ,n ,n1 natches4 ,the ends are joined to the body by means of offsets and the first step is the construction of these4 ,one half of the block is taken and laid upon its back1 being supported by clay so that the face is level and steady4 ,an offset plate is now cut to fit each end4 ,to make these a piece of plaster is selected or made which is true and smooth on both sides4 ,the plates are cut of the same width as the mold and are beveled at the upper edge so as to rise slightly from the mold face4 ,the curve at the end of the mold is cut out to fit and beveled in like manner4 ,then two end plates are fitted4 ,these should be about two inches higher than the offset plates and are square at the top4 ,upon each of these two or three clay natches are set1 being placed low down near the face of the mold4 ,the mold and plates are well sized and bound together with side walls just as in the making of the mold4 ,plaster is poured to a height sufficient to well cover the natches and left to set hard4 ,no shaping is necessary4 ,when well set the end plates and offset plates are removed but the vase mold and the case are left attached together4 ,the other half of the mold is prepared and run in the same way1 the same offset plates and end plates being used with such slight refitting as may be necessary4 ,the work is now examined and all rough places and scraps of adhering plaster are removed4 ,the two halves of the case1 the half molds being still attached1 are set up on end1 back to back1 being separated by a thin piece of plaster or a strip of cardboard which should extend two inches above the top4 ,the top ends are now sized1 the natch holes having been smoothed off1 a band of paper is tied around and plaster poured on top to a depth of about one inch4 ,when set the whole is turned over and the operation is repeated on the other end4 ,after the final setting the ends are easily removed and by the insertion of a thin knife driven by a light blow1 the molds and case are separated4 ,each half case is now laid on its back and the proper ends are fitted in place4 ,it only now needs the usual side walls to be tied on and molds can be made with ease just as the original block mold was made4 ,illustration3 ,fig4 #aj4 ,mold and case in position4 ,the top ends are lifted to show fitting4 ,the bottom ends are not shown4 ,it now remains to make a case of the bottom mold4 ,the bottom piece of the block mold is taken and sized and with a strip of paper bound around it1 plaster is poured4 ,the two are detached when set and the case is finished4 ,it consists of seven pieces2 three are used in each half and one for the bottom4 ,illustration3 ,fig4 #aa4 ,block of plaster with face of plate turned4 ,b1 height of plaster to be poured4 ,c1 rubber belt4 ,thus equipped it is possible to make any number of working molds and if the case should wear out or be damaged1 a new one can always be made from the block mold4 ,the block mold itself1 having been sized1 is no longer absorbent and cannot be used for making vases4 ,the working molds should be thoroughly dried before using and they will last longer4 ,flat ware1 such as plates and saucers1 is made on1 not in1 a mold4 ,the diameter of the plate having been decided upon1 a block of plaster three inches wider is run4 ,this is placed on the center of the wheel or jigger and in it the face of the plate is turned4 ,this must be sunk below the level of the block and when finished1 must appear as though the plate itself were embedded in the plaster4 ,one half of the thickness of the edge is shown in such a way that there is no under cutting4 ,just outside of this edge the plaster is turned so as to slope gently up to the level of the block4 ,without removing the block from the wheel the face of the plate is well sized1 a band of belting is arranged1 of the same diameter as the edge of the slope and plaster is poured to a depth of three inches4 ,out of this the back of the mold is turned as shown in the illustration 7,fig4 #ab74 ,illustration3 ,fig4 #ab4 ,a1 block of plaster4 ,b1 mold poured on face of plate and turned4 ,the top of this as it lies upside down is shaped with a straight1 almost upright slope which enables the mold to be set securely in the wheel head4 ,around the exposed edge of the original block1 three or four natches are now bored or cut4 ,they should be placed at irregular distances so that there will be no doubt as to the putting together of the sides of the case4 ,if two circular pieces of plaster have to be set together and held by natches there should always be either this irregular spacing or some distinctive mark1 because if this be not provided for1 two or three trials will always be made before the correct fitting is found and these trials wear out the natches very quickly4 ,illustration3 ,fig4 #ac4 ,a1 bottom of case4 ,b1 ,cavity for pouring molds4 ,c1 top of case4 ,the back of the plate mold and the edges of the block are now sized and plaster is run to the level of the highest part of the mold but no higher 7,fig4 #ac74 ,when this is set1 the two halves of the case can be separated and the mold taken out4 ,now when the halves of the case are fitted together there will be a cavity the exact size of the mold4 ,this can be filled again and again with plaster1 a new mold being formed each time4 ,illustration3 ,fig4 #ad4 ,iron prong to fit wheel head4 ,illustration3 ,fig4 #ae4 ,a1 plaster1 with prong inserted4 ,b1 rubber belt4 ,in order to use these molds a special head must be provided for the wheel4 ,the regular head of the wheel should be detachable and in its place an iron frame called a prong is fitted4 ,this consists of a collar either with a hollow cone or a screw to fit the shaft of the wheel1 and from this radiate four short arms4 ,in order to use this a circular block of plaster some two or three inches thick is poured on a table or slab and just as this is setting1 the prong1 upside down1 is pressed into it just below the surface and held there until the plaster is hard enough to support the weight of the iron4 ,when hard1 the whole is lifted and the prong with the plaster attached is set in position on the wheel4 ,this now forms a rough plaster head and it must be turned true4 ,in this head a circular depression is to be turned which will exactly fit the back of the plate molds4 ,if the recess should wear larger as it will if much used1 a new head can easily be run4 ,the same principle can be applied to the making of molds for saucers4 ,illustration3 ,fig4 #af4 ,wheel head with plate mold4 ,the tool used is shown in dotted outline4 ,cups and bowls are molded from the outside4 ,a block of plaster about one inch thicker than the height of the proposed cup is taken and centered upon the wheel4 ,out of this the piece is to be turned1 upside down1 leaving a ledge or platform1 the outside diameter of which is the size of the mold4 ,the rubber belt is tied around this and the mold poured4 ,if for casting this will suffice1 but if it is intended to make the cups upon the wheel the outside of the mold must be turned to fit a wheel-head which is hollowed to receive it4 ,the making of the cups is described in ,chapter ,,xi4 ,a bowl is simply an enlarged cup4 ,,chapter ,,viii3 ,,building ,,by ,,hand ,the production of pottery by hand is a form of modeling but with the important difference that while pieces modeled by art-school methods are not intended to be preserved in the clay itself1 built pieces are destined for the fire4 ,it is therefore necessary not only that a special clay be used but that the work be such as will hold under the strain of the burn4 ,the composition of the clay has been dealt with in another chapter and it is presumed that the worker has decided upon the proper mix or has procured a suitable clay4 ,there are two possible treatments of built pottery2 the work may be finished by fingers and tools only or it may be placed upon the wheel and turned to a true surface4 ,in the latter case the result is much the same as if the piece were thrown on the wheel as will be described4 ,the principal point of difference is that while building needs less practice than throwing1 turning a built piece is much more difficult and tedious than turning a thrown one4 ,it is almost impossible to build with sufficient accuracy for the work to run true1 and a great deal of time is consumed in filling hollows and removing lumps4 ,these do not appear obtrusive when the work is held in the hand1 but if it be revolved upon a fixed center every slight irregularity appears to be accentuated4 ,on the other hand the charm of built ware lies in the subtle plastic quality which belongs to no other material or method4 ,for very large pieces such as tree pots the combination method is useful but these should be built on the wheel itself and kept true as the work proceeds4 ,then a slight turning at the finish1 when the clay is leather hard1 will produce a satisfactory result4 ,the clay for building should be rather soft as it is apt to dry quickly on handling4 ,the work may be done either with coils or pieces4 ,a plaster bat should be made with a low dome in the center4 ,this bat may either fit the wheel or not1 depending upon the plan adopted4 ,the dome is to raise up the bottom of the vase and form a foot4 ,the table may be covered with a piece of oil cloth or may be kept slightly damp4 ,the first attempt should be to build a cylinder as this form is easy to construct and to keep true1 so that the attention may be devoted to the manipulation of the clay4 ,it is first necessary to roll out the clay into cords which should be a little thicker than the proposed walls are to be4 ,these cords should be as uniform as possible and should be rolled quickly to avoid undue hardening4 ,it is best to roll them as required4 ,the domed bat is made quite damp and upon it should be marked the diameter of the cylinder to be built4 ,a roll of clay is taken1 one end laid in the center of the bat and the rest is coiled around it in a spiral line4 ,when the disc so formed has reached the proper size1 the coils are gently rubbed over with the fingers until they have thoroughly united and the lines of the spiral have disappeared4 ,the clay disc may now be turned over and the rubbing continued on the other side4 ,the circle is cut true and a new coil is laid on the outer edge thus making a shallow circular tray4 ,in raising the walls it is best to pinch off the roll of clay when one circle has been completed and the new roll should be begun at another point so that all the joints will not be at the same place4 ,this plan is better than coiling a long roll in a spiral for in this case one side of the piece will be higher than the other4 ,after three rolls have been laid in position the wall1 both inside and out1 should be worked like the bottom so that the rolls will disappear and the clay be welded uniformly together4 ,this should be done without water or with as little as possible4 ,the use of water is very tempting4 ,it makes the clay so smooth and seems to help but it will inevitably make the work sloppy and will tend to soften the walls4 ,after three or four rolls have been worked in1 the piece should be laid aside for some hours to stiffen4 ,if this be not done the weight of the second building will cause the work to sag and fall out of shape4 ,for this reason it is well to have two or three pieces in hand at once so that there need be no waiting4 ,when the cylinder is of sufficient height it should be allowed to become quite stiff and then the irregularities should be corrected with a little soft clay which is worked into the joints4 ,the whole surface may now be gone over with tools and brought to the required finish4 ,as soon as the clay is hard enough it should be removed from the damp bat and placed upon a dry one to become dry4 ,in the method of building by pieces no rolls are prepared but the clay is taken1 pinch by pinch1 each morsel being pressed into place as the work goes on4 ,this plan is somewhat more plastic in effect and is well adapted to free-hand work2 the resulting pottery1 however1 is generally thicker and heavier4 ,the craft of building is not mastered until the lines of a drawing can be successfully followed4 ,the clay is apt to choose its own way and the result will be very different from what the potter intended4 ,the design should be carefully worked out on paper1 full size if possible1 and the clay form should be compared with the drawing as the building goes on4 ,a profile may be cut in cardboard and this1 applied to the clay from time to time1 will verify the line1 but all such mechanical aids should be used sparingly as the value of this work depends largely upon the sense of freedom and self-expression which belongs to it4 ,the thickness of the clay walls is a matter of great importance4 ,a small piece should not be so thick as to feel clumsy and heavy1 nor should a large piece be so thin as to lose the sense of strength and solidity4 ,it may be found on drying the ware1 that cracks1 especially in the bottom1 are developed4 ,the cause of this may be in the clay4 ,a clay which is too plastic or too fine in the grain will surely crack4 ,such a clay may be opened or meagered by the addition of ground flint or fine grog4 ,the cause may1 on the other hand1 be in the building4 ,if the welding of the coils or pieces be imperfectly done1 cracks are sure to result4 ,if the bottom be too thick it will crack4 ,a great strain is put upon the bottom in drying4 ,the clay must be able to shrink and while the side walls are able to settle down on themselves1 the bottom is pulled in every direction by the sides4 ,the bottom should be made quite thin in the center and thicker toward the edges4 ,this will help to avoid cracks4 ,a bad crack cannot be successfully mended4 ,it is best to break the piece and begin again4 ,to burn it means the loss of the clay but the clay will be saved if the damaged work be withheld from the kiln4 ,a small crack on the edge is also hopeless4 ,a crack showing on the edge of a piece is a bad fault4 ,a small crack in the bottom may be mended by dampening the place carefully and pressing in a little stiff clay4 ,,chapter ,,ix3 ,,the ,,potter',s ,,wheel ,much of the glamour of the potter's art is associated with the wheel4 ,poets have sung its praise and artists have delighted in its rhythmic motion1 but alas6 the wheel as a commercial method of manufacture is doomed to extinction4 ,it cannot compete with the precision and speed of machinery4 ,it devolves1 therefore1 upon the artist potter to maintain the wheel in its rightful place as1 par excellence1 the potter's tool4 ,no clay worker's studio should be without a wheel1 but the particular form of wheel depends upon the nature of the circumstances under which it is to be employed4 ,the simplest wheel is that used by the ,chinese4 ,a circular plate with a heavy rim is set upon a spindle so that it will revolve freely and run steadily4 ,as the workman sits or kneels upon the floor the surface of the wheel is about at the floor level4 ,around the periphery and upon the upper surface four holes are sunk and the workman1 inserting a short stick into one of these1 gives the wheel a rapid motion4 ,then while it is revolving by its own momentum the clay is centered and shaped4 ,as the motion is lost the stick is again inserted and the wheel spun4 ,this method1 of course1 involves much skill on the part of the workman4 ,in the next form1 one which is only adapted1 however1 for crude experimental work1 the wheel is set upon the frame of a sewing machine and operated by the treadle4 ,a beginning may be made upon such a wheel but the operator will soon wish for something better4 ,a common factory form and one which is well adapted for studio work is the kick wheel4 ,the wheel head is set at the top of a spindle and in the upright shaft there is a crank to which is attached a horizontal moving treadle4 ,this is worked continuously by the left foot1 the weight of the body being supported by the right4 ,the action is strenuous and scarcely fitted for persons of other than robust physique but it can be used successfully after practice4 ,this wheel is made by the manufacturers of potter's machinery4 ,another form of the kick wheel is used in ,europe and is1 in fact1 the original wheel used by the ,french and ,german potters in the seventeenth century4 ,the head is set on a spindle as usual but instead of the crank there is a large heavy disc on the bottom of the shaft and revolving in a horizontal plane4 ,this is within reach of the foot and the operator1 being seated1 imparts a rapid motion by pushing1 usually with the ball of the right toe4 ,the momentum is kept up by the weight of the disc and there is a great advantage in that the foot need not be in continuous motion4 ,on the other hand it is difficult to acquire sufficient speed and power for the work4 ,there are several forms of machine wheels which are entirely satisfactory but which need the application of power4 ,if a gas engine or a water motor or electric current be available1 every effort should be made to obtain a wheel of this description4 ,the prime motion is imparted to a short horizontal shaft which moves at a constant speed4 ,then the operator1 seated in comfort1 regulates the speed of the wheel itself by pressure upon a treadle4 ,no action is required but a simple pressure1 light for a slow speed and heavy for rapidity4 ,where the electric current is available1 nothing could be better4 ,self-contained motor-driven wheels are available but are rather expensive4 ,one more plan may be mentioned in which the wheel is simply a vertical lathe with a belt and handle to be turned by an assistant4 ,this may be convenient for some but it is not always possible to secure help at the moment when the wheel is to be used4 ,moreover the cost of labor would soon pay for a mechanical wheel4,g ,g ,information as to the usual types of wheel may be obtained from ,the ,crossley ,manufacturing ,company1 ,trenton1 ,n4 ,j42 ,the ,patterson ,foundry and ,machine ,company1 ,east ,liverpool1 ,ohio2 a wheel operated like a sewing machine is sold by the ,lewis ,institute1 ,chicago4 ,whatever type of wheel is selected it should be arranged with a head which can be removed4 ,there are two methods of constructing this2 the head may be screwed on to the spindle1 or the latter may terminate in a cone-shaped plug upon which the wheel head is made to fit as in the illustration 7,fig4 #ad74 ,the latter plan is to be preferred as the head can be removed more quickly and is not so likely to work loose4 ,several heads for the wheel can then be provided1 one for regular work1 one for making plates1 one for finishing and so forth4 ,the regular operation performed upon the wheel is termed either throwing or turning according to the industry in which it is employed1 but in this description the word throwing will be used because the subsequent operation in which tools are employed is best described as turning4 ,the best head for the wheel to be used in throwing is made of hard wood or brass because the ball of clay can be easily centered upon a smooth surface4 ,this1 however1 involves that the work shall be cut off with a wire and removed while soft4 ,this is commonly done by professionals but is beyond the skill of the beginner4 ,it is best1 therefore1 to use a head like that illustrated for plate making and to have a number of specially shaped plaster bats to fit the recess 7,fig4 #ag74 ,then when the piece is formed1 the bat with its burden can be set aside for the work to harden4 ,illustration3 ,fig4 #ag4 ,wheel head with detached bat4 ,throwing is not an easy operation to describe but the following instructions in the form of lessons will1 with a large amount of practice1 enable the student to become fairly expert4 ,every opportunity should be taken to watch a good potter at work4 ,there are a thousand and one little tricks in the position of the arms1 hands1 thumbs and fingers which are impossible to describe but which can easily be copied4 ,if a kick wheel be used some time must be given to practicing the motion without using clay4 ,the action of the foot must become subconscious or automatic like the pedaling of a bicycle so that simply to will a change of speed is to accomplish it4 ,illustration3 ,fig4 #ah4 ,the progress of a clay ball on the wheel4 ,lesson ,i4 ,take the bat about to be used1 plunge it in clean water and soak it nearly1 but not quite1 to saturation4 ,if the bat remain wet one minute after being taken from the water1 it has soaked too long and must be dried off a little4 ,the effect of a wet bat is that the clay slips and cannot be held in one place4 ,the proper dampness is secured when the clay ball can be pushed along the surface of the bat but does not slip easily4 ,this condition is important and should be secured by experiment1 because if not right1 good work will be impossible4 ,illustration3 ,,plate ,i4 ,,throwing4--,,lesson ,,ii1 #a4 ,illustration3 ,,plate ,,ii4 ,,throwing4--,,lesson ,,ii1 #b4 ,lesson ,,ii4 ,place a small basin of water close at hand4 ,take a ball of clay about three inches in diameter4 ,set it on the center of the wheel as nearly as can be judged4 ,now spin the wheel at a fairly rapid rate4 ,brace the left elbow against the side and1 wetting the hand1 press the ball of the thumb and the lower part of the palm against the clay4 ,the left forearm being kept rigid1 the clay as it revolves will be forced into the center of the wheel4 ,use the right hand to sprinkle water on the clay that proper lubrication may be maintained4 ,with the fingers of the right hand pull the clay towards you1 at the same time pressing inward with left hand and so squeezing the clay4 ,as the hands come together the clay will rise in a cone4 ,do not pull it upwards but let it rise as it is squeezed4 ,now bring the hands over the top and with the thumbs together press down again4 ,lumps and irregularities will be felt in the clay and the operations of spinning up and pressing down must be continued until these disappear4 ,repeat the exercise of centering with a fresh ball of clay until it can be accomplished with ease and rapidity4 ,the clay so used is not wasted4 ,the superfluous water may be dried off upon a plaster bat and the clay wedged up for use again4 ,illustration3 ,,plate ,,iii4 ,,throwing4--,,lesson ,,ii1 #c4 ,this wedging or waging of clay--the word has descended from the old ,english potters--is important4 ,a strong table should be built of which the top1 measuring about #cj by #bj inches1 is made of two-inch plank4 ,a raised edge two inches high is fastened firmly by being nailed to the sides2 the trough thus formed is then filled with plaster and allowed to harden4 ,an upright post is fastened in the center of one side and from the top of this a fine brass wire is stretched to the other side of the table1 thus making a diagonal4 ,the worker stands at the side of the table opposite the post4 ,the ball of clay is taken in both hands and cut in two against the wire1 then the pieces are slapped smartly upon the plaster1 one on top of the other4 ,the whole lump is then lifted1 cut in two and slapped down as before4 ,the lump of clay is thus formed into layers1 the irregularities in hardness are corrected and the clay made smooth4 ,a little practice will make the work quite easy but it will often be found necessary to cut and beat the clay fifteen or twenty times before a good texture is secured4 ,if the plaster table be dry the clay will be stiffened rapidly but the plaster may be made wet to prevent this if it should not be necessary4 ,a clay may also be softened in this way by sprinkling it with water as the wedging goes on4 ,illustration3 ,,plate ,,iv4 ,,throwing4--,,lesson ,,iii1 #a4 ,illustration3 ,,plate ,v4 ,,throwing4--,,lesson ,,iii1 #b4 ,lesson ,,iii4 ,center the ball as in ,lesson ,,ii and moisten both hands and the clay4 ,grasping the clay lightly but with sufficient force1 press the right thumb downwards and towards the palm and a cup-shaped hollow is formed in the clay4 ,raise the right hand slowly1 still keeping a light pressure upon the clay with the thumb4 ,the clay wall will rise with the hand4 ,now insert the two first fingers of the left hand into the hollow and hold them against the right-hand wall4 ,slacken the speed of the wheel a little4 ,bend the forefinger of the right hand and press the second joint and the knuckle against the outer wall so as to oppose the fingers which are inside4 ,press the thumbs together to steady the hands and raise both hands upwards together4 ,the fingers inside and outside the clay should be kept at a definite distance apart so that as the hands rise1 the clay is brought to a uniform thickness4 ,the hands are brought steadily to the full height to which the clay will go and thus a cylinder is formed4 ,repeat this lesson three or four times with fresh clay4 ,illustration3 ,,plate ,,vi4 ,,throwing4--,,lesson ,,iv1 #a4 ,illustration3 ,,plate ,,vii4 ,,throwing4--,,lesson ,,iv1 #b4 ,lesson ,,iv4 ,keep the hands wet4 ,shape the clay cylinder as directed in the previous exercise4 ,now repeat the action of the fingers inside and outside and1 beginning at the bottom1 take a closer grip of the clay and draw up the walls as before4 ,the cylinder is now taller and the walls thinner4 ,do this again and again taking a little closer grip each time until the cylinder is as tall and as thin as the clay will bear4 ,the walls will probably spread as the work proceeds and the hands must then be used outside4 ,grasp the clay with both hands and squeeze it slightly2 at the same time raise the hands upwards4 ,this will reduce the diameter of the cylinder and thicken the walls4 ,the operation of the fingers can then be repeated until the full height is reached4 ,there is1 of course1 a limit to the height of the cylinder which can be made from a given lump of clay and it is best to begin on a small scale4 ,a ball of clay which can be easily grasped with the hands is the proper size with which to learn4 ,a very small ball is nearly as hard to work as a large one4 ,repeat this lesson until a tall cylinder can be made with ease and certainty4 ,illustration3 ,,plate ,,viii4 ,,throwing4--,,lesson ,v4 ,lesson ,v4 ,keep the hands wet4 ,spin up a cylinder with thick walls as in ,lesson ,,iii4 ,with the fingers of the one hand inside and those of the other hand outside1 open the cylinder gradually4 ,keep the wheel at a slow speed4 ,if the edge runs unevenly1 use both hands outside to steady it1 then work outwards again until a shallow bowl is formed4 ,illustration3 ,,plate ,,ix4 ,,throwing4--,,lesson ,,vi1 #a4 ,lesson ,,vi4 ,keep the hands wet4 ,spin up a cylinder of medium height as in ,lesson ,,iv4 ,with the fingers of the right hand outside press inwards at the base of the cylinder close to the bat and with the fingers of the left hand inside1 press outwards at a slightly higher level4 ,this will reduce the diameter at the bottom and increase it in the middle1 making a cup shape4 ,now raise the right hand and gently draw the top inwards4 ,with the left hand inside press the upper edge outward and with the fingers of the right hand shape the upper part into the form of a jar or flower pot4 ,illustration3 ,,plate ,x4 ,,throwing4--,,lesson ,,vi1 #b4 ,illustration3 ,,plate ,,xi4 ,,throwing4--,,lesson ,,vii4 ,lesson ,,vii4 ,keep the hands wet2 proceed as in ,lesson ,,vi4 ,instead of making the top flange outwards1 draw it gradually inwards into a globe form4 ,work the clay carefully upwards and inwards until the opening at the top is almost closed4 ,several attempts will probably have to be made before this result can be secured4 ,illustration3 ,,plate ,,xii4 ,,throwing4--,,lesson ,,viii1 #a4 ,lesson ,,viii4 ,keep the hands wet4 ,spin up a globe shape with a narrow base as in ,lesson ,,vi but carry a good share of the clay to the top so that the upper edge of the globe is quite thick4 ,insert two fingers of the left hand and with the fingers of the right hand outside work the upper edge of the globe into a tall neck4 ,the action is the same as in the shaping of a cylinder except that the diameter is smaller4 ,a good deal of practice will be necessary in order to keep the neck thin and to raise it to any appreciable height1 but perseverance will accomplish it4 ,illustration3 ,,plate ,,xiii4 ,,throwing4--,,lesson ,,viii1 #b4 ,these lessons if carried out conscientiously will enable the operator to produce almost any form in so far as the manipulation of the clay is concerned but the work up to this point is drill only4 ,it is not intended that the pieces should be preserved4 ,the next point is to insist that the clay obey the potter in the shaping of a form4 ,a simple drawing of a jar should be made exact to the size proposed4 ,two or three pairs of calipers are provided and with them the diameter of each part of the drawing is taken4 ,of course a single pair could be made to serve1 but it is very inconvenient to change measurements while working4 ,a piece of wood also is cut to the height of the proposed piece4 ,the throwing is begun as usual by making a cylinder4 ,this should be higher than the drawing for the clay sinks in the shaping4 ,first the bottom is pressed into the proper size 7,lesson ,,vi74 ,then the body is enlarged to the required measure and1 lastly the diameter of the top is taken and the height brought to the determined point4 ,if too high the superfluous clay may be cut off with a pointed knife1 the edge being carefully rounded afterwards4 ,it is only by checking up one's work in some such way as this that real power can be acquired4 ,the skilled worker can think in the clay and create forms at will upon the moving wheel1 but for the beginner to attempt this is like an endeavor to paint pictures before one has learned to draw4 ,shape after shape should be designed1 drawn to scale and thrown to measure2 in fact1 for elaborate pieces no other course is possible4 ,,chapter ,x3 ,,turning ,it is not possible to finish work to perfection in the operation of throwing4 ,the clay is too soft to handle and for proper finishing the piece must be turned over to get at the bottom4 ,an experienced thrower reduces the final work to a minimum and this1 of course1 is the ideal plan but even in factory practice every thrown piece is passed on to the turner so that the phrase thrown and turned is used as of a single operation1 though it1 in fact1 expresses not only two processes but the work of two men4 ,the artist-potter must needs1 therefore1 learn to turn1 though this process should not be worked to death as it is liable to be4 ,many persons in the pride of having produced some sort of a form on the wheel will leave it in the crudest possible condition and trust to the turning tool to remove defects4 ,if the lessons on throwing have been conscientiously carried out1 this error will not be committed4 ,a half dozen cylinders of convenient size should be thrown on separate bats and set aside in a cool place to harden4 ,they must not be dried but should be in the condition known as leather hard4 ,if thrown one day they will be ready for turning the next morning4 ,pieces thus hardened are no longer flexible4 ,they can be handled freely and the clay can be easily cut with a knife4 ,illustration3 ,fig4 #ai4 ,turning tools bent and sharpened4 ,the equipment for turning consists of a board support1 a turning stick and a set of tools4 ,the board is of soft pine1 eight or ten inches wide and two feet high and is set upright at the back of the wheel frame opposite the workman4 ,it may be screwed in position if it does not interfere with the throwing1 or it may be set in a socket so as to be removed when not in use4 ,its purpose is to support the end of the turning stick4 ,the stick is an ordinary broomstick in the end of which is a sharpened nail4 ,in use the end of the stick is held in the left hand and the point is pressed into the board at any required height4 ,the right hand1 holding the tool1 is rested on the stick just as the hand of a painter rests on the mahl-stick4 ,the turning tools are of soft steel4,h ,they are purchased unshaped and the potter must learn to bend and file them to suit himself4 ,a section of bench should be set apart for filing and care must be taken that the steel dust does not get into the clay4 ,h ,the ,milligan ,hardware ,company1 ,east ,liverpool1 ,o4 ,one of the cylinders1 with the bat upon which it was thrown1 is now taken in hand4 ,many beginners try to turn their pieces without detaching them from the bat1 trusting to the original adhesion to hold the piece in position4 ,this is a very unsatisfactory plan4 ,a fundamental principle in craft work is that the mechanical difficulties in manipulation should be met and overcome at the first4 ,if one trusts to some method which is apparently easy one walks with crutches and there will come a time1 if progress is to be made1 when such helps must of necessity be abandoned and then the learning must be begun again4 ,therefore the student is advised to face the mechanical technique at the very beginning4 ,the cylinder may be turned on the throwing bat1 but there is a better way4 ,the piece should not become so hard that it will release its hold on the bat but with a long bladed knife it should be cut away4 ,if the knife be held close to the bat a separation is easily effected4 ,set the leather-hard cylinder upon a new bat which is slightly damp and which runs true1 on the wheel4 ,the first problem is to center the work4 ,a pencil line may be run upon the bat making a circle just the size of the cylinder4 ,then as the wheel is revolved it will be seen if the piece runs true4 ,it is quite unlikely that this will be the case4 ,perhaps the bottom is true but the top circle is untrue4 ,in other words1 the axis of the cylinder is not upright4 ,turn the cylinder upside down and try if it will run any better4 ,if it does the work may be begun in this position4 ,if it does not1 turn it back again4 ,now take a pencil and hold it with a steady hand so that it just touches the near side as the wheel goes round4 ,lift up the edge of the cylinder on the side marked by the pencil and slip a morsel of clay under it4 ,revolve the wheel and try with the pencil again4 ,in this way raise or press down one side1 keeping the bottom circle in the center until both top and bottom are running as nearly true as they can be made4 ,this1 so far1 refers only to the horizontal planes4 ,if one side is higher than the other it does not matter at present4 ,now take three small pieces of soft clay1 and1 holding the cylinder firmly with one hand1 press them down at equidistant points in the angle where the piece joins the bat4 ,this serves to hold the work in position4 ,a square turning tool of small size is the best to begin with4 ,it is held in the fingers as a pen is held but more firmly4 ,the right hand rests on the turning stick and1 the connection between hand and stick being as rigid as possible1 both are moved together4 ,this is better at first than moving the right hand freely for to do so will surely result in irregular work4 ,the tool should be held so as to cut with one corner at first and it is well to take one cut1 remove the tool1 take another cut and so on4 ,the object should be to feel the clay and to test its resistance4 ,no one can be a successful potter who does not cultivate a sympathy for the clay4 ,the tool is to cut1 not to scrape4 ,that is1 the cutting edge is to be opposed to the revolving clay4 ,the point at which the tool touches the clay is opposite the center or at the same distance from the operator as the center of the wheel is4 ,if nearer to the workman the tool will not cut2 if further away1 it will scrape and pull 7,fig4 #e1 page #ej74 ,the first efforts should be directed towards acquiring skill4 ,the student should endeavor to make a cut at any desired point without regarding the effect upon the shape of the cylinder4 ,in other words the clay is used merely as a practice piece4 ,it is not to be preserved4 ,it is a good plan to keep on turning the first piece until it is all turned away4 ,too many students fail because they wish to have a piece to keep4 ,he will make the best ultimate success who cares nothing for the preservation of a dozen or two cylinders or other shapes1 but uses them merely as exercises in manipulation4 ,if the student is over anxious to avoid spoiling his work1 he grows nervous and so loses control of his tools and material4 ,to set no value on the practice pieces themselves begets confidence and this is the surest aid to success4 ,after two or three cylinders have been centered to the pencil line the attempt to center one free-hand may be made4 ,place a cylinder on the wheel but not quite in the center4 ,spin the wheel at a medium rate4 ,fix the attention upon the eccentric motion1 trying to forget the circular motion4 ,as the cylinder appears to move from side to side tap it lightly with the hand so as to drive it towards the center4 ,in all probability this will result in driving the cylinder off the wheel altogether4 ,some little practice is needed1 but if persevered in the result will be a power of convenient and rapid centering which is never forgotten and which is the greatest possible help to successful work4 ,one may practice with a wooden cylinder or even a tin can if the weight approximates that of the clay pieces4 ,illustration3 ,fig4 #bj4 ,turned feet4 ,a ,b ,c1 feet for small pieces4 ,d ,e ,f1 feet for large pieces4 ,g ,h ,i1 common faults in foot finish4 ,accompanying the practice in turning there should be some exercise in the shaping and filing of tools4 ,broad tools filed to the proper curve are indispensable in finishing concave surfaces4 ,a curved edge may also be put upon one or two narrow tools4 ,these will cut more rapidly than the broader ones but will not leave as smooth a finish4 ,whatever tool be used the final surface must be worked over with a soft sponge and water so as to eliminate the tool marks and leave a plastic surface4 ,one of the principal troubles with which the beginner will meet is the vibration of the tool known as chattering4 ,this is sometimes so slight as not to be felt by the hand but when the motion of the wheel is stopped the work will be found covered with fine ridges like gathering on muslin4 ,the way to prevent this is to avoid using the broad edge of the tool until some experience has been gained4 ,the way to cure it is to go over the work again with a fine pointed tool and then to use the sponge liberally4 ,the point of the tool cuts through the small ribs or wrinkles whereas a broad tool would ride over them and make the trouble worse4 ,while the whole surface of the work will probably need more or less turning1 the chief part of the operation is concerned with the under part or foot4 ,the formation of a good foot marks a good potter and vice versa4 ,before beginning to turn it should be decided what kind of a foot is desired4 ,each shape has its own style4 ,some sketches are given here with an idea of the form to which each is adapted4 ,they are shown upside down because the work is done in this position4 ,the small bevel at the outer angle is used for facility in glazing4 ,a foot finished thus always has a neat appearance when the glaze has been removed from the beveled face4 ,,chapter ,,xi3 ,,making ,,large ,,pieces ,there is a limit in size beyond which the non-professional will not be able to go4 ,men of life-long experience can throw very large jars but this involves not only more practice than the artist-potter can hope to secure but also great physical strength4 ,on the other hand it is perfectly possible to form vases two or three feet in height by doing the work in parts or sections4 ,no one need fear to put such a plan in operation on account of sentiment4 ,it is1 of course1 worth while to make large wares in a single piece but section work involves great skill and1 as a rule1 the result attained is better4 ,work made in one piece is apt to be badly finished1 especially inside1 and unduly heavy4 ,work made in sections can be thrown with thin walls and finished with proper care4 ,if tradition be of any help1 be it known that the ,chinese have used the piece method for hundreds of years1 and that the ,greeks used it three thousand years ago4 ,the first requisite is a drawing either actual size or properly scaled4 ,the measurements should be those of the soft clay and if a particular size be desired in the burned piece1 the shrinkage1 probably about one-eighth1 must be added4 ,the drawing must show the size of each section with the points of junction1 and should indicate the upper and lower edges in each case4 ,some divisions are best made right side up2 some are more easily thrown upside down4 ,care should be taken that the faces which are to be joined are thrown under similar conditions4 ,in every piece of work one face rests on the bat1 the other is in the air or free4 ,a bat face should always be joined to a bat face and a free face to a free4 ,suppose1 for instance1 a vase is to be sixteen inches high and is to be thrown in four divisions of four inches each4 ,the bottom division is made first4 ,this will stand in its normal position1 right side up4 ,the second section must now be thrown upside down1 because1 if it were not1 its bat face would be joined to the free face of the first piece4 ,so the sections are thrown alternately1 every other one being inverted4 ,illustration3 ,,plate ,,xiv4 ,,making ,,large ,,pieces4 ,,the ,,first ,,section4 ,as the pieces are thrown they must be carefully measured to see that the faces which are to be united are the same size4 ,the height of each piece also must be gauged and adjusted4 ,the bats with their contents are now set aside to harden4 ,as soon as they can be handled with safety the clay pieces should be removed from the bats upon which the throwing was done and set upon dry bats which will absorb the moisture and help to stiffen the clay4 ,it is a good plan to pile the sections up as they are to stand in the finished piece1 one upon another and to leave them so in a cool place for ten or twelve hours4 ,the faces which are to be joined will thus acquire a uniform hardness and unequal shrinkage will be avoided4 ,when all is ready for the turning1 the sections being of the proper hardness are taken in hand4 ,this work should not be hurried4 ,it will take a whole morning to put together a large piece4 ,first1 the bottom section is placed on the wheel1 centered and made to run true as regards the top edge4 ,it is then inverted and the foot is properly finished1 signed and dated4 ,then the second joint is likewise turned true on both faces1 the inside turned smooth2 and so on1 each piece in turn is prepared for the fitting1 the measurement of each face being accurately adjusted4 ,at this stage it is possible to correct the diameter of the faces to some extent either by pressure as the wheel revolves or by building up with soft clay4 ,in either case1 however1 the new work must be hardened before proceeding4 ,the whole piece is now put together carefully but with dry joints4 ,it should be slowly revolved on the wheel and the proportions carefully criticised4 ,if satisfactory it is taken apart again and the actual fitting up may proceed4 ,the bottom section is again centered most carefully on the wheel and steadied with three pieces of clay4 ,a thick slip is now prepared1 the same clay as that used for the work being of course1 used4 ,this slip must be quite free from lumps and should be as thick as molasses4 ,the upper edge of the work is carefully sponged with clean water and a good coating of slip is applied at the junction4 ,care must be taken that every part of the face is covered with slip4 ,the second joint is now moistened at the junction and set in position upon the bed of slip4 ,it is placed very lightly and the wheel is gently revolved to see if the running is true4 ,if so it is pressed home and the superfluous slip is removed4 ,the joint should be quite close like a glued joint in carpentry4 ,in the same way the third section is placed upon the second and the fourth upon the third4 ,it is now possible to work over the face of the vase with a little soft clay4 ,there is almost always some irregularity in the line1 especially at the joints1 and this must be adjusted while the work is moist4 ,then the whole face is gone over with turning tools and sponge and the vase is set aside to dry4 ,it must not be expected that large pieces1 made by any method1 will be produced with as much ease as small vases and bowls4 ,the risks are much greater and1 owing to the size of the work1 the faults are much more apparent4 ,when the vase is perfectly dry it should be set on the wheel1 centered and slowly revolved4 ,if it is very untrue in its motion there is no remedy4 ,it should be broken down and the clay used again4 ,a very slight irregularity may be corrected by rubbing off a little clay on one side of the foot but this cannot be done to any considerable extent4 ,the courage to break unsatisfactory work is never more valuable than at this juncture4 ,it will pay in the end1 for no imperfect piece can be a source of satisfaction to the conscientious craftsman4 ,illustration3 ,,plate ,,xv4 ,,making ,,large ,,pieces4 ,measuring the ,foundation of the ,second ,section4 ,illustration3 ,,plate ,,xvi4 ,,making ,,large ,,pieces4 ,drawing up the ,second ,section4 ,illustration3 ,,plate ,,xvii4 ,,making ,,large ,,pieces4 ,shaping the ,third ,section4 ,illustration3 ,,plate ,,xviii4 ,,making ,,large ,,pieces4 ,the ,three ,sections ,completed4 ,illustration3 ,,plate ,,xix4 ,,making ,,large ,,pieces4 ,turning the ,edge of the ,first ,section4 7,note the other sections on the table47 ,illustration3 ,,plate ,,xx4 ,,making ,,large ,,pieces4 ,finishing the ,bottom of the ,first ,section4 7,note the second section in the foreground ready for turning47 ,illustration3 ,,plate ,,xxi4 ,,making ,,large ,,pieces4 ,checking the ,size of the ,second ,section4 ,illustration3 ,,plate ,,xxii4 ,,making ,,large ,,pieces4 ,fitting ,together ,dry4 ,illustration3 ,,plate ,,xxiii4 ,,making ,,large ,,pieces4 ,setting the ,third ,section in ,place4 ,illustration3 ,,plate ,,xxiv4 ,,making ,,large ,,pieces4 ,the ,three ,sections ,set ,together in the ,rough4 ,illustration3 ,,plate ,,xxv4 ,,making ,,large ,,pieces4 ,the ,finished ,vase4 ,,chapter ,,xii3 ,,cups ,,and ,,saucers ,,and ,,plates ,it is not likely that many craftsmen will care to produce table wares or even that they will be able to acquire the necessary skill4 ,simple as these wares seem1 they are1 in fact1 the most difficult of all to make well4 ,in factory working1 one man makes nothing but cups1 another saucers and another plates1 so that each attains the skill of constant practice1 but this is out of the question for the studio worker4 ,at the same time it is well to know how it is done and it may be that some one will undertake to produce a few pieces for the sake of the enjoyment arising therefrom4 ,it is possible to finish a cup upon the wheel just as a vase is made4 ,the handle is modeled in clay and fastened in place with slip when in the leather hard condition4 ,saucers and plates cannot be made in this manner2 first1 because the broad thin bottom will surely crack and1 second1 because it is impracticable to turn a plate or saucer over in order to finish the bottom4 ,the risk of breakage is so great that there is nothing to be gained4 ,if cups be needed of uniform size they must be molded4 ,the making of the molds has already been described4 ,a small cylinder of the proper size is thrown in clay and removed from the wheel while soft4 ,a number of these should be made at one time so as to avoid changing the wheel head often4 ,when all are ready a hollow head shaped to receive the cup mold is set on the wheel and a mold inserted4 ,one of the soft cylinders is now lowered gently into the mold and as the wheel is revolved the soft clay is pressed firmly against the walls with the fingers4 ,a piece of wood1 called a rib1 cut to the exact shape of the inside of the cup1 is used to smooth off the interior4 ,the top edge is cut off and rounded and the mold is set aside for the cup to harden4 ,as soon as the cup can be turned out it is set upside down upon the wheel and the bottom turned4 ,another method dispenses with the formation of the cylinder or lining4 ,a ball of clay of the proper size is dropped into the mold and pressed into shape with the fingers1 the wheel1 of course1 being spun4 ,the finishing is accomplished with the rib as before4 ,this method will answer for wares which are to receive a low fire but for high temperatures the clay must be handled by the first-named plan4 ,the cup is not complete without a handle4 ,this may be modeled as already stated but to make each one of half a dozen in this way is unduly tedious4 ,the better plan is to model a handle in wax and make a mold as already directed4 ,a roll of soft clay is then laid in the mold1 the two halves pressed together and the handle taken out and finished4 ,care must be taken that cup and handle are of the same degree of moisture1 leather hard1 for choice1 or they will part company as they dry4 ,the fastening is done with thick slip4 ,the method for saucers is the same as that for plates1 so that one description will suffice4 ,the first step is to make a tool or profile4 ,a large handful of soft clay is rolled out into a thick cylinder and laid down upon the plate mold4 ,it should extend from the center to the circumference1 forming a radius of the circle4 ,the clay is pressed closely to the surface of the mold and part of it is squeezed into a knob which will form the hand-hold of the tool 7,fig4 #af1 page #ff74 ,the clay is left in this position until it becomes nearly but not quite dry4 ,it is then taken off and whittled into shape4 ,the front edge must be straight and must lie along a radius of the plate4 ,the foot is cut in at the proper point and a broad wedge-shaped hollow is made so as to gather the clay and pile it up into the foot4 ,the hand-hold is shaped so as to fit comfortably between the first and second fingers of the right hand4 ,when properly shaped the tool is thoroughly dried and then burned in the kiln4 ,the fire must not be severe as it is important not to shrink the tool to any great extent4 ,after burning slight corrections can be made with a file or a hard stone4 ,the heel of the profile must be exactly at the center of the plate and the toe or curve must rest on the outer edge of the plate mold4 ,in making plates a batting block and batter are used4 ,the former is a heavy block of plaster which is fixed to a strong table4 ,it must be saturated with water when in use4 ,the wedging table already described will serve for this4 ,the batter is a disc of plaster to which a handle is attached4 ,it may be made of a thick plaster block1 the handle being cut out of the substance itself4 ,this is also kept saturated with water so that the clay will not stick4 ,a ball of clay is laid on the block and gently beaten out with the batter into a disc of the proper size and thickness4 ,the face of this is then polished with a steel blade and the disc is then lifted1 turned over and laid1 polished side downward1 upon the mold4 ,the wheel is then revolved and the clay pressed firmly to the mold with wet hands4 ,the tool is now dipped in water and pressed steadily upon the revolving clay4 ,the heel must be adjusted accurately to the center and the foot will be seen to rise up in its proper place4 ,the operation is not easy and many failures must be expected but practice will accomplish the desired result4 ,when leather hard the plate is gone over with a thin piece of rubber and when quite hard it may be removed from the mold4 ,the edge is now trimmed and the face sponged over and the plate is ready for the kiln4 ,,chapter ,,xiii3 ,,casting ,in commercial production the casting method is constantly used4 ,it is a means of making light and delicate pieces with ease and1 of course1 all the pieces cast in the same mold are alike4 ,this very fact1 however1 has led to the method being disregarded by the studio worker who does not wish to duplicate anything that he makes4 ,if a single piece only is to be made the work involved in molding is a waste of time and it is better to strive for skill at the wheel1 and yet there are occasions when a knowledge of casting is of great value4 ,in the preparation of trial pieces there is no method better4 ,to make these in sufficient number on the wheel would be tedious except for the benefit of the practice involved4 ,directions for making molds have already been given and the slip which will have been prepared in the process of clay making is ready for the casting process4 ,this slip should be thick1 about the thickness of buckwheat batter4 ,to be accurate1 a pint should weigh #bf ounces4 ,for small pieces or for vases with narrow necks it is advisable to use the slip rather thinner4 ,for large wares1 on the other hand1 or for open bowls it may be slightly thicker4 ,a few experiments will show the reason for this4 ,two quart jugs are needed4 ,they should be large of neck and should deliver their contents freely and completely4 ,jugs with a deep shoulder are not good as the slip hangs in the pouring4 ,one of these jugs is filled with slip which is to be poured carefully from one to the other1 allowing it to flow gently down the side4 ,this is to break the air bubbles which are nearly always found to be present and the pouring should be repeated until the slip flows smooth and even4 ,the mold1 being thoroughly dry1 is tied around with twine1 if in parts1 and wedged firmly so that it cannot leak4 ,the slip is then carefully poured so as not to touch the sides and the mold is filled until a small mound of slip rises over the edge4 ,this mound will at once begin to sink as the water is drawn into the walls of the mold and slip must be added1 little by little1 to make good the loss4 ,a small quantity of clay will now be found to have stiffened at the rim of the mold and if this be carefully removed with a steel tool the thickness of the wall of the vase will be seen4 ,if not thick enough the mold must be continually filled up until the necessary thickness is attained4 ,the mold is then carefully lifted1 making sure that the bottom is held firmly1 and the slip is poured out4 ,it should not be poured back into the casting-jug but into another vessel4 ,the mold is now set upside down to drain4 ,it should not be placed upon the table but upon two sticks laid parallel so that the drip may hang clear4 ,several molds may be filled in this way at one time and after about twenty minutes the one first filled may be opened4 ,the bottom is gently detached and the upper part of the mold1 consisting of two halves1 is laid upon the table on its side4 ,a little gentle manipulation will now suffice to lift the one half and the vase will be seen lying in the other half as in a cradle4 ,the clay is still very soft and must be treated carefully4 ,the half mold1 with the contained vase1 is taken in the left hand and held nearly upright1 the fingers below1 the thumb on the top4 ,now set the fingers of the right hand under the bottom of the vase1 rest the thumb lightly against the side and tilt the half mold gently forward4 ,if mold and clay are in good condition the vase will fall forward to be supported on the fingers of the right hand and steadied by the thumb4 ,the half mold is now laid down and the vase taken in both hands1 set gently on a plaster bat and put aside to dry4 ,it often happens that the vase leaves the mold with reluctance4 ,if the slip be very new1 or the mold either damp or hard or worn out there will be some difficulty in effecting a separation4 ,by allowing the work to stand a while1 however1 and by slightly jarring the mold from time to time with the ball of the thumb the piece can generally be removed without damage4 ,in using a new mold it is customary to make what is called a waste filling4 ,the mold is filled with slip and at once emptied4 ,after standing a few minutes it is forcibly opened and the thin layer of clay inside is picked out with a ball of plastic clay pressed against it4 ,a tool should never be used as this will damage the face of the mold4 ,if the clay should stick obstinately a soft cloth used over the finger will remove it4 ,the reason for this waste filling is that it removes the scum which occurs on all new molds4 ,cast ware should not be touched until quite dry and then the spare at the neck is carefully cut off1 the seams scraped down and the whole surface smoothed with fine sand paper and a soft cloth4 ,worn out linen serves excellently for this purpose4 ,cups and bowls1 if molded1 are made without spare at the top4 ,in this case great care must be taken to see that the edge is left clean and smooth in the casting4 ,the spare neck on a vase acts as a margin of safety1 as it is completely cut away in the finishing4 ,if a piece has no spare the edge must be left without blemish at the first4 ,,chapter ,,xiv3 ,,tiles ,there are two methods of making tiles1 the dust-pressed method and the plastic4 ,the former is the more usual commercial plan but the appliances for preparing the dust and the heavy presses necessary are not adapted to studio work4 ,the dust-pressed tile is1 moreover1 somewhat mechanical in surface4 ,it is not suitable for modeling or for any treatment but those of glaze and color4 ,the plastic tile1 on the other hand1 may be treated by plastic methods and the surface offers a texture which appeals strongly to the artist4 ,for the successful production of tile a special body is necessary4 ,ordinary pottery clay is too close in grain and straight tile cannot be made from it4 ,small square pieces1 however1 such as tesser1 can be made from any clay4 ,it is presumed that a pure white tile body is not required4 ,for studio work the most pleasing white surface is found in an opaque enamel1 but for the most part the craftsman will wish to work for colored tile4 ,a cream or buff body is all that is necessary1 therefore1 and the foundation of this is a clay known as sagger clay4 ,in order to secure the necessary porosity a fine grog must be used4 ,grog is burned clay4 ,after working awhile there will be an abundance of this in broken unglazed pottery but at first some soft fire-bricks must be pounded4 ,this is laborious work1 but a boy can usually be hired to do it4 ,the brick or broken pottery is crushed in an iron mortar but should not be broken too fine4 ,two sieves are necessary1 one of #bj and one of #dj meshes to the linear inch4 ,the coarse powder which passes through the #bj mesh and lies upon the #dj mesh is used4 ,this is called #bj-dj grog4 ,the dust which passes through the #dj mesh may be saved for kiln work4 ,it is useful for setting biscuit pieces one upon another as it will effectually prevent sticking4 ,this powdered grog is also useful in the case of flowing glazes4 ,a thick layer on the bottom of the kiln will catch any drops of glaze and save the kiln from damage4 ,a quantity of the #bj-dj grog having been prepared1 a mixture should be made of3-- ,sagger ,clay #eej parts #bj-dj ,grog #cjj parts ,ground ,flint #aej parts ,the clay should be finely pulverized and the whole mixed in the dry state4 ,water is then added1 little by little1 until a rather soft mass is obtained4 ,it is not practicable to mix clay of this description by the slip method because the grog would settle out and fall to the bottom of the vessel4 ,it sometimes happens1 however1 that the stoneware clay contains grains of iron which cause black spots to appear in the tile4 ,if these cause trouble the clay must be made into slip first and lawned through #abj mesh4 ,it is then allowed to become very thick and the grog is stirred in4 ,this is a good deal more trouble than the first named plan and is not often necessary4 ,tile are sometimes made in plaster molds4 ,a tile of the proper size is cut from a plaster block and a mold is made from it4 ,if a modeled surface be desired clay may be modeled upon the face of the plaster tile before the mold is made4 ,the mold will then receive the embossment in reverse and all the tiles made from this mold will be alike4 ,the clay is pressed into the mold while quite soft and is scraped off level at the back4 ,thus it is the face of the tile that is shaped by the plaster4 ,if this plan be adopted the tile must be removed from the mold as soon as possible4 ,if left to dry in the mold they will warp because of the unequal absorption4 ,a better method has been devised by the author and has been put into practice with considerable success4 ,when the size of the proposed tile has been determined a board is made which is large enough to hold a square of the tile1 say twelve or sixteen4 ,thus if a tile five inches square is to be made the board would be fifteen by twenty inches for twelve tile or twenty inches square for sixteen4 ,on each side of the board a wooden rim is fastened and this must stand higher than the board to the exact thickness of the tile4 ,about five-eighths of an inch is enough4 ,the board must be perfectly rectangular and marked off at even distance of five inches and a shallow groove is cut at each point4 ,to make the tile the board is wetted and an even coating of grog dust is sprinkled upon it4 ,a ball of clay is laid in the center of the board and rolled out with a rolling pin to fill every part of the frame4 ,with a straight edge the clay is struck off smooth and clean1 working always from the center outwards4 ,reversing the plaster mold method the tile are now face upward and any kind of surface may be given at will4 ,the clay may be lubricated with water and made smooth or it may be sprinkled with grog dust which will give a sandy or toothed finish4 ,the square is now to be cut into tile and this is done with a slender knife and ruler4 ,the ruler should not rest upon the clay but upon thin strips of wood or cardboard which may be laid along the edges for the purpose4 ,the cutting should not go quite through the clay as1 if a slight connection be allowed to remain at the bottom1 the tile will keep each other straight4 ,when the cutting is finished the board should be set at an angle of forty-five degrees for the clay to harden4 ,when leather-hard the whole may be turned gently over and the tile allowed to fall on to a board placed in readiness4 ,they are now broken apart1 trimmed if necessary and set aside to dry4 ,tile made in this way can be kept straight without difficulty and the method is much more expeditious than pressing in plaster molds4 ,if a modeled surface be intended it is quite easy to work on the tile in the tray while the clay is soft4 ,forms may be cut in wood and pressed into the clay in any variety and the charm of individual treatment is preserved4 ,the body given above will prove quite porous when fired but it will take matt glazes well4 ,a little crazing is no detriment to tile because they are not like vessels which are meant to hold water4 ,if a denser body be wished for some of the flint may be replaced by spar4 ,one of the most attractive methods of decorating tile is by means of a white or delicately tinted enamel and color4 ,the opaque tin enamel given on page #acd will answer well and if the whiteness prove too intense it may be modified by a very small addition of under-glaze color according to the tint desired4 ,the tile should be glazed rather thick4 ,not as thick as a matt glaze but thicker than bright glazes4 ,the glaze or enamel should be poured into a flat tray which is large enough to receive one tile4 ,the tile is taken by the edges between fingers and thumb and held face downwards4 ,do not let either fingers or thumb project beyond the face4 ,the glaze having been well stirred the face of the tile is allowed to rest upon it for about two seconds4 ,the hand is then lifted quickly and reversed so that the tile is face upwards4 ,every effort should be made to avoid streaks or tears and a little practice will accomplish this4 ,if the glaze shows a bad surface it should be scraped off4 ,it can be mixed up and used again4 ,sometimes a slight wetting of the tile before glazing will help the surface to flow evenly4 ,the decoration is carried out with ordinary under-glaze colors4 ,these may be mixed together to produce any hue which is sought and a little of the glaze itself1 about ten per cent41 should be mixed with the color4 ,this will assist in uniting the color with the glaze so that they melt together4 ,to produce enamel decorations at their true value the color should be painted upon the dry glaze before it is burned4 ,the best relation between surface and color is thus secured4 ,the color must be worked quite thin with water and a little glycerine4 ,a quick1 sure stroke is needed as no change or erasure is possible4 ,the design may be made on paper and traced or pounced on to the glaze with lamp-black4 ,for burning the tile there is nothing better than little fire-clay boxes4 ,these can be made in a mold without difficulty and the inside of each should be washed with glaze4 ,if some such protection be not provided dirt is almost sure to fall on the flat surface and the tile will be spoiled4 ,it is not possible to rear them on edge in the kiln for burning as then the glaze would flow to the lower side and cause an unsightly ridge4 ,,chapter ,,xv3 ,,glazes ,,and ,,glazing ,,part ,i ,much of the fascination of pottery making centers in the glaze4 ,at one time a great deal of mystery appeared to surround the composition and use of glazes1 but if one will take the trouble to learn1 much of this may be dispelled4 ,some knowledge of chemistry is desirable if an understanding of the theory of glaze-making is to be acquired1 but a good deal may be learned even without this knowledge4 ,only such simple instruction as can be assimilated by ordinary intelligence will be attempted here1 as an exhaustive treatment of the subject would be long and tedious4 ,it is possible to purchase glazes ready for use,j but the true craftsman will not be satisfied until he can prepare his own4 ,j ,the ,roessler ,hasslacher ,chemical ,company1 #gji #fth ,avenue1 ,new ,york ,city1 manufacture glazes according to the recipes of the author1 and also chemicals for use in the laboratory4 ,glazes,k belong to a class of chemical compounds known as silicates2 that is1 they have silica as the characteristic ingredient4 ,clear glazes are compound silicates of lead1 zinc1 lime1 potassium1 sodium1 aluminum and boron4 ,matt glazes are characterized by certain of these ingredients being present in excess2 and stanniferous or tin glazes are1 as the name implies1 rendered opaque by the use of oxide of tin4 ,k ,it is admitted that glazes are not chemical combinations but solid solutions1 but the principle is more easily understood when the analogy of chemical action is adopted4 ,the commonest type of glaze is that which is made from ready prepared1 commercial substances4 ,these are called raw glazes as being made from raw materials or materials which need no preparation4 ,it is possible to mix a glaze in a druggist's mortar by hand1 using fine sieves1 but if the best results are to be secured1 a small mill must be used for grinding4 ,the best form of mill is the ball mill or jar mill4 ,this consists of a porcelain jar which is set in a frame and made to revolve upon its axis in a horizontal position4 ,it is about half filled with porcelain balls and these as they roll against each other perform the grinding4 ,these mills may be purchased ready for use1 either as a single jar to be worked by hand or a battery of two or more revolved by power4,l ,l ,paul ,o4 ,abb1 #cj ,broad ,street1 ,new ,york ,city4 ,a good pair of scales is a necessity and it will be found convenient to use metric weights which need no calculation into pounds and ounces4 ,suspended scales are not as easy to use as the form known as counter scales or balances4 ,they should have movable pans which are usually nickel plated4 ,upon these the materials can be placed direct without the use of pieces of paper1 which are always troublesome and inaccurate4 ,there should be a graduated bar on the front for the adjustment of weights of five grams and under4 ,this avoids the use of small weights which are always being mislaid and lost4 ,dealers in chemical supplies keep these scales in stock and the cost is about eight dollars4 ,a set of weights must also be procured from one hundred grams to five grams inclusive4 ,these need not be of the accurate adjustment which are used in analysis4 ,a good inexpensive grade is sufficient4 ,the ingredients for glazes are given in the following list3 ,commercial ,chemical ,symbol or ,equivalent ,name ,name ,formula ,weight ,white ,lead ,lead ,carbonate ,pb7,,oh7#bb,pb,c,o#c #beh ,zinc ,oxide ,zinc ,oxide ,zn,o #ha ,soda ,ash ,sodium ,carbonate ,na#b;,,co#c #ajf ,niter ,potassium ,nitrate ,,kno#c #bjb ,whiting ,calcium ,carbonate ,ca,c,o#c #ajj 7,carbonate of ,lime7 ,feldspar ,orthoclase ,k#b,o1,al#b,o#c1f,si,o#b #eeg ,kaolin ,aluminum ,silicate ,al#b,o#c1b,si,o#b1b;,h#b,o #beh or ,china ,clay ,flint ,silica ,si,o#b #fj ,borax ,sodium di ,borate ,na#b;,b#d,o#gaj;,h#b,o #chb ,boric ,acid ,boric ,acid ,b#b,o#cc;,h#b,o #abd ,for coloring1 the following metallic oxides are used3 ,color ,chemical ,symbol or ,equivalent ,name ,formula ,weight ,blue ,cobalt ,oxide ,co,o #hj ,blue and ,green ,copper ,oxide ,cu,o #gi ,gray and ,brown ,nickel ,oxide ,ni,o #ge ,brown and ,yellow ,iron ,oxide ,fe#b,o#c #afj ,brown ,manganese ,carbonate ,mn,c,o#c #aae ,under-glaze colors may also be used for coloring glazes1 the color being ground with the glaze batch4 ,it is not absolutely necessary to commit the formula and equivalent weight to memory4 ,they will soon be remembered as use becomes second nature4 ,a glaze is usually expressed as the chemical formula4 ,in this there are three divisions given1 each of which expresses a distinct function4 ,on the left hand are the bases1 the foundation of the glaze4 ,these indicate the type1 such as lead glaze1 a lime glaze1 an alkaline glaze1 etc4 ,all glazes being silicates1 this is the usual way of distinguishing them4 ,in the center are the alumina and boron oxide4 ,these regulate the behavior of the glaze in the fire4 ,they make it viscous or sluggish as it melts and prevent a too rapid flow4 ,the alumina is infusible1 the boron is fusible1 but boron cannot be used in a raw glaze for reasons to be presently explained4 ,at the right stands the silica1 the dominating factor with which all the other ingredients combine1 and which controls the behavior of the whole as regards the fitting of the glaze to the body4 ,the very simplest form of glaze is a bisilicate of lead1 represented by the formula ,pb,o1 ,si,o#b1 or one equivalent of lead oxide and one of silica4 ,the term equivalent means that the mixture is calculated1 not upon the actual weight of a substance but upon its equivalent or unit weight4 ,thus the equivalent weight of lead oxide1 ,pb,o1 being #bbb1 in order to produce the formula in actual weight #bbb grams or pounds must be weighed out4 ,it does not matter what weights are used so long as they are the same for all4 ,in like manner the equivalent weight of silica is #fj and as flint is pure silica1 the formula ,pb,o1 ,si,o#b would be produced by weighing-- ,litharge or ,lead ,oxide #bbb parts ,flint or ,silica #fj parts ,litharge is not1 however1 a convenient substance to use4 ,it is very heavy and does not mix well in water4 ,the most usual substance for the introduction of lead oxide is white lead4 ,this is not lead oxide but it changes to lead oxide when burned4 ,white lead bears the formula ,pb7,,oh7#b1 #b,pb,c,o#c1 which1 being dissected is found to be #c,pb,o1 ,h#b,o1 #b;,,co#b4 ,h#b,o is water and ,,co#b carbonic acid1 both of which pass off in burning4 ,both1 however1 are weighed when the white lead is put on the scales and therefore the equivalent weight of white lead is #beh and not #bbb4 ,the mixture for practical purposes then would be-- ,white ,lead #beh parts ,flint #fj parts ,which1 when ground and spread upon the ware would be a very fusible glaze of a yellowish tone4 ,this was spoken of as a bisilicate of lead because the measure of the silica1 also called the acidity of a glaze1 is calculated upon the oxygen contained in the base and the silica respectively4 ,pb,o contains one molecule of oxygen1 ,si,o#b contains two4 ,hence the relationship of the oxygen in the base to the oxygen in the silica is as one to two4 ,this is called simply the oxygen ratio and is of great importance in determining the behavior of a glaze4 ,while this simple bisilicate of lead will be a glaze under certain conditions it is found to possess two faults4 #a4 ,it is too fluid under fire4 ,the glaze will run down a vertical surface and leave the upper edge of the piece bare4 #b4 ,if subjected to a long slow fire it will lose its gloss and become devitrified4 ,this devitrification is often seen in commercial work and appears as a dull scum in patches and around the edges of the ware4 ,it is1 in fact1 a crystallization of the silica which separates out1 as salt does from an evaporated brine4 ,both these faults may be corrected by the addition of a little alumina to the glaze4 ,a whole equivalent of alumina would be too much1 in fact it is found in practice that 4#b equivalent is sufficient for most lowfire glazes4 ,in order to maintain the oxygen ratio and to keep the glaze as a bisilicate the silica content must be raised4 ,alumina contains three molecules of oxygen so that the total amount of alumina is multiplied by three and the silica brought to the equal point thus3 ,pb,o1 4#b;,al#b,o#c1 #a4f,si,o#b ,the amount of silica required in any bisilicate glaze may be found by the following equation3 ,si,o#b #b7c;,al#b,o#c #a7_/b ,thus if the alumina content were 4#be equivalent this would be expressed3 ,si,o#b #b74ge #a7_/b ,or-- ,si,o#b #c4ej_/b #a4ge equivalent ,now in order to produce this as a mixture it would be possible to introduce the alumina in the pure state1 but pure alumina is expensive and clay which contains alumina is cheap so that clay is generally used to supply the alumina4 ,clay1 however1 contains silica as well1 and therefore allowance must be made for this4 ,on referring to the formula for kaolin1 the purest form of clay1 ,al#b,o#c1 #b,si,o#b1 #b;,h#b,o1 it will be seen that there is twice as much silica present in equivalence as there is alumina and therefore 4#b kaolin will contain 4#b;,al#b,o#c and #d,si,o#b4 ,subtracting1 then1 the #d,si,o#b from the #a4f,si,o#b needed there will be #a4b left to be supplied in the form of flint4 ,the mixture therefore is-- ,white ,lead #a4j #beh #beh ,kaolin 4#b #beh #ea4f ,flint #a4b #fj #gb ,this is a glaze of the same character as that first given except that it no longer flows unduly from the higher places nor will it devitrify in a long-continued fire4 ,the alumina will have counteracted both these evils4 ,a glaze with only lead oxide as the base is not1 however1 desirable for general use4 ,the color is yellowish and the lead oxide is apt to destroy the hue of any colors which are used with it4 ,the available bases may be classified under three heads4 #a4 ,the metallic oxides1 lead and zinc oxides4 #b4 ,the alkaline earths1 the oxides of calcium and barium4 #c4 ,the alkalies1 potash and soda4 ,barium oxide is not often used and soda cannot be used in raw glazes because there is no convenient substance which contains it4 ,as glazes are always ground in water only insoluble ingredients can be employed without preparation4 ,potash is found in feldspar which is insoluble and while there is a so-called soda feldspar it can rarely be obtained of sufficient purity4 ,in arranging the bases with which to compose a glaze it is desirable to use one at least from each class1 but it must be borne in mind that however many bases are introduced the total must always be unity4 ,this unit is1 for the sake of brevity1 described as ,,ro4 ,for example the following groups may be set forth3 #a4 ,pb,o ,lead ,oxide 4#g ,ca,o ,calcium ,oxide 4#c --- ,,ro #a4j #b4 ,pb,o 4#f ,ca,o 4#d --- ,,ro #a4j #c4 ,pb,o ,lead ,oxide 4#e ,zn,o ,zinc ,oxide 4#b ,ca,o ,calcium ,oxide 4#c --- ,,ro #a4j #d4 ,pb,o 4#f ,zn,o 4#a ,ca,o 4#c --- ,,ro #a4j #e4 ,pb,o ,lead ,oxide 4#f ,ca,o ,calcium ,oxide 4#c ,k#b,o ,potassium ,oxide 4#a --- ,,ro #a4j #f4 ,pb,o 4#ej ,ca,o 4#ce ,k#b,o 4#ae ---- ,,ro #a4jj #g4 ,pb,o ,lead ,oxide 4#de ,zn,o ,zinc ,oxide 4#aj ,ca,o ,calcium ,oxide 4#cj ,k#b,o ,potassium ,oxide 4#ae ---- ,,ro #a4jj #h4 ,pb,o 4#ce ,zn,o 4#ae ,ca,o 4#ce ,k#b,o 4#ae ---- ,,ro #a4jj ,the reason for the unit rule is that if one formula is to be compared with another there must be a uniform basis upon which to work and1 furthermore1 it makes no difference whether the silica combines with one1 two1 three1 or four bases1 the chemical action is the same and1 so long as the sum of the bases is kept at unity1 the same amount of silica will be required4 ,if two glazes be taken as an illustration this will be made clear3 ,pb,o 4#f ,ca,o 4#d --- ,al#b,o#c 4#b ,si,o#b #a4f #a4j ,pb,o 4#df ,zn,o 4#ab ,ca,o 4#bh ,k#b,o 4#ad ---- ,al#b,o#c 4#b ,si,o#b #a4f #a4jj ,both of these formulae are bisilicates and each being properly fired1 will stand1 without crazing1 on the same body4 ,the use of the formula is to give an insight into the composition of the melted glaze4 ,it takes no account of volatile ingredients or losses in the fire but for this very reason it must be translated into the substances to be weighed before use can be made of it4 ,of the ingredients given on pages #adb1 #adc1 some contain but one item of the formula1 others contain several1 as in the case of kaolin already cited4 ,feldspar1 of the variety known as potash feldspar and named by mineralogists1 orthoclase1 is a very useful ingredient in raw glazes1 being1 in fact1 almost the only source of potash4 ,the formula1 page #adb1 shows that a molecule or equivalent of feldspar contains one molecule of potash ,k#b,o1 one of alumina ,al#b,o#c1 and six of silica ,si,o#b4 ,this fact is taken into account in calculating the mixture or batch weight4 ,base ,no4 #e 7page #adh71 is as follows3 ,pb,o 4#f ,ca,o 4#c ,k#b,o 4#a ---- #a4j ,and this made up into a bisilicate glaze would be3 ,pb,o 4#f ,ca,o 4#c ,k#b,o 4#a ---- ,al#b,o#c 4#b ,si,o#b #a4f #a4j ,these items are extended in a horizontal line1 a space being left on one side for the list of ingredients4 ,pb,o ,ca,o ,k#b,o ,al#b,o#c ,si,o#b 4#f 4#c 4#a 4#b #a4f ,addition 4#f ,white ,lead 4#f ---------------------------------------- ,subtraction 4#j 4#c 4#a 4#b #a4f ,addition 4#c ,whiting 4#c ---------------------------------------- ,subtraction 4#j 4#a 4#b #a4f ,addition 4#a 4#a 4#f ,feldspar 4#a ---------------------------------------- ,subtraction 4#j 4#a #a4j ,addition 4#a 4#b ,kaolin 4#a ---------------------------------------- ,subtraction 4#j 4#h ,addition 4#h ,flint 4#h ---------------------------------------- ,subtraction 4#j ,each item is thus disposed of until the list is complete4 ,these figures are1 however1 given in equivalents and each must be multiplied by the equivalent weight of the substance used4 ,white ,lead 4#f #beh #aed4h parts by weight ,whiting 7calcium carbonate7 4#c #ajj #cj4j ,feldspar 4#a #eeg #ee4g ,kaolin 4#a #beh #be4h ,flint 4#h #fj #dh4j ----- #cad4c ,batch of ,glaze ,these amounts are weighed out in grams1 put upon the mill with half a pint of water1 and ground for about an hour4 ,when taken off1 the jar and porcelain balls are washed with plenty of water and the washings saved4 ,the glaze1 thus diluted1 is strained through a lawn of #abj mesh and laid aside to settle4 ,the clear water is then siphoned or poured off and the glaze is ready for use4 ,for glazing the glaze should be as thick as cream4 ,a finger dipped into it should show a white coating which cannot be shaken off4 ,the pottery to be glazed should be first soaked in clean water until all absorption has ceased4 ,it is then wiped dry and plunged into the glaze bath1 or1 if the piece be large1 the glaze may be poured over it4 ,the piece is gently shaken to distribute the glaze evenly and it is then set aside to dry4 ,before glazing a piece everything should be prepared4 ,a stilt or support upon which to set the wet glazed pottery1 and a bowl of water in which to wash the fingers so as to save all the glaze4 ,it will be found best to glaze the inside of the piece first4 ,it should then be well shaken to remove as much glaze as possible before beginning the outside4 ,a thick glaze inside is almost sure to run down to the bottom where it will form a pool and perhaps burst the piece4 ,before firing1 the bottom of the pottery should be carefully trimmed4 ,any excess of glaze is removed and the point of contact with the table is sponged clean4 ,then1 when the piece is set in the kiln the bottom will not be inclined to stick4 ,,part ,,ii3 ,,matt ,,glazes ,the texture of the matt glaze is always pleasing and the artist is not content unless at least some of his work can be finished in this way4 ,matt glazes are not underfired glazes nor are they deadened by acid or sand blast4 ,they are produced in two ways4 ,first1 by an excess of alumina which is believed to cause the formation of certain compounds in the glaze1 and1 second1 by an excess of silica which produces a devitrified surface4 ,it was mentioned in the last chapter that a glaze free from alumina will devitrify or become dull4 ,this is undesirable when a glaze is intended to be brilliant but it may be controlled and turned to advantage in the production of a certain type of matt4 ,the successful preparation of this silica matt is extremely difficult4 ,in fact1 in the studio kiln it is almost impossible4 ,these small kilns are apt to cool with great rapidity whereas1 in order to produce the silica matt the kiln must be cooled very slowly1 hours and even days of cooling being sometimes necessary4 ,the alumina matt is more simple and its texture is quite satisfactory1 being1 in the opinion of some1 the more pleasing of the two4 ,it was mentioned in the last chapter that the best bright glazes for low temperature work are bisilicates1 having an oxygen ratio of #a3b4 ,the alumina matt has an oxygen ratio of about #c3d4 ,this is secured in the following manner4 ,the ,,ro content may consist of any of the bases used in bright glazes1 the proportion of each being adjusted in accordance with the desired point of fusion4 ,the alumina content is rather higher than in a bright glaze and should not fall much below 4#c equivalent1 4#ce equivalent is even better4 ,the silica is adjusted in accordance with the following equation3 ,si,o#b #c7c;,al#b,o#c #a7_/d ,now if the alumina content be placed at 4#ce equivalent this would work out3 ,si,o#b #c7a4je #a7_/d ,or3 ,si,o#b #f4ae_/d #a4ecge ,but as such a complete fraction is not necessary it may be stated as #a4ed equivalent4 ,the formula would therefore be3 ,,ro1 ,al#b,o#c 4#ce1 ,si,o#b #a4ed ,the ,,ro content should not be too fusible4 ,lead oxide is desirable up to about 4#e equivalent and it is an advantage to use feldspar so that ,k#b,o may be introduced4 ,calcium oxide is also good but zinc oxide must be used sparingly as it is apt to suffer if overfired4 ,the high content of alumina necessitates a good deal of clay and as this1 if used raw1 would make the glaze too plastic and cause it to crack1 it is best to calcine a part of it1 thus removing the combined water and changing the equivalent weight from #beh to #bbb4 ,the calculation will then proceed as in the case of a bright glaze4 ,pb,o 4#ej ,ca,o 4#ce ,k#b,o 4#ae ---- ,al#b,o#c 4#ce ,si,o#b #a4ed ,,ro #a4jj ,pb,o ,ca,o ,k#b,o ,al#b,o#c ,si,o#b 4#ej 4#ce 4#ae 4#ce #a4ed ,addition 4#ej ,white ,lead 4#ej #beh #abi ---------------------------------------- ,subtraction 4#j 4#ce 4#ae 4#ce #a4ed ,addition 4#ce ,whiting 4#ce #ajj #ce ---------------------------------------- ,subtraction 4#j 4#ae 4#ce #a4ed ,addition 4#ae 4#ae 4#ij ,feldspar 4#ae #eeg #hc ---------------------------------------- ,subtraction 4#j 4#bj 4#fd ,addition 4#ae 4#cj ,calcined ,kaolin 4#ae #bbb #cc ---------------------------------------- ,subtraction 4#je 4#cd ,addition 4#je 4#aj ,kaolin 4#je #beh #ac ---------------------------------------- ,subtraction 4#j 4#bd ,addition 4#bd ,flint 4#bd #fj #ad ---------------------------------------- ,subtraction 4#j ,the mix1 therefore1 is3 ,white ,lead #abi grams ,whiting #ce ,feldspar #hc ,calcined ,kaolin #cc ,kaolin #ac ,flint #ad ,this will give a silky matt glaze1 nearly white1 maturing at about cone #a4 ,if a lower fusing point is desired the white lead may be increased at the expense of the whiting or if the glaze prove too fusible the reverse will correct it4 ,the flint may be omitted without damage4 ,the grinding of a matt glaze is of great importance4 ,it is better to have it too coarse than too fine4 ,grinding for one hour on the ball mill should be ample and if the glaze be then strained through #abj mesh lawn all coarse particles will be arrested4 ,a glaze that is too fine will crack and peel off or will curl up in the kiln4 ,more than half the success of matt glazes lies in the using4 ,it is necessary that the coating of glaze be very thick or the true texture will not be developed4 ,when the glaze is taken from the mill plenty of water may be used in order to wash the apparatus clean and to save all the glaze4 ,this is set aside in a deep bowl to settle4 ,after some hours the clear water is carefully drawn off with a siphon4 ,half an ounce of gum tragacanth is put to soak in a quart of clean water4 ,after twelve hours the gum will have swollen to a jelly-like mass4 ,this is now worked vigorously with a ,dover egg-beater or in a ,christy mixer and again set aside4 ,after another twelve hours the operation is repeated and the solution is a clear syrup of the consistency of thin molasses4 ,a drop or two of carbolic acid or other germicide should be added to prevent decomposition4 ,this mucilage should be prepared in advance4 ,to the glaze batch from which the water has been removed a tablespoonful of the mucilage is added4 ,if more of the glaze than the single batch has been weighed out then more mucilage will be necessary4 ,the mixture is to be stirred very thoroughly and it will be found to thicken under the hand4 ,it must be very much thicker than the bright glaze4 ,in fact1 the thicker it is the better1 only that it must flow sufficiently so that the pottery may be covered with a smooth coating1 avoiding lumps4 ,matt glazes do not correct their own faults in the kiln as bright glazes do4 ,every finger mark will show and1 consequently1 the glazing must be done with the greatest care4 ,the process is the same as that described for bright glazes1 except that as much glaze as possible is left on the ware4 ,no more shaking should be done than will suffice to secure a smooth coating4 ,it is well to place the pieces upside down to dry4 ,for the inside of the pieces a matt glaze may be used or a thin coat of clear glaze at the pleasure of the worker4 ,if the latter1 care must be taken that none of the inside glaze is allowed to run over the edge4 ,in firing1 the pottery is sometimes placed on a stilt but this is not absolutely necessary4 ,for a support a flat piece of burned clay may be used and this should be covered with an infusible wash to prevent any possibility of sticking4 ,equal parts of kaolin and flint make a good wash4 ,the wash is worked up with water into a slip and applied with an ordinary brush4 ,,part ,,iii3 ,,fritted ,,glazes ,fritted glazes1 like raw glazes1 are clear and brilliant and for most purposes the latter will suffice4 ,since1 however1 the aim of this work is to give as complete information as may be the fritted glaze will not be omitted4 ,a fritt is a melt or compounded glass and the purpose of it is to permit the use of certain ingredients which are not available in the raw state4 ,as glazes are ground in water it is essential that the substances used be insoluble4 ,this condition would prohibit advantage being taken of borax1 boric acid1 and soda ash1 if it were not for the possibility of rendering these insoluble by the operation of fritting4 ,the following is an example of a fritted glaze3 ,pb,o ,lead ,oxide 4#cj ,zn,o ,zinc ,oxide 4#ae ,al#b,o#b ,alumina 4#ae ,ca,o ,lime 4#be ,si,o#b ,silica #b4fe ,b#b,o#c ,boric ,acid 4#dj ,na#b,o ,soda 4#bj ,k#b,o ,potash 4#aj ,this will be produced in accordance with the usual calculation by the mix3 ,white ,lead 4#c #beh #gg ,zinc ,oxide 4#ae #ha #ab ,whiting 4#be #ajj #be ,borax 4#bj #chb #gf ,feldspar 4#aj #eeg #ef ,kaolin 4#je #beh #ac ,flint #a4ie #fj #aag ,the borax contains the required amount of both soda and boric acid and the potash is supplied by the feldspar4 ,borax1 being soluble1 must be melted with certain other ingredients into an insoluble glass1 thus3 ,fritt3 ,borax #gf x #b #aeb ,whiting #be x #b #ej ,feldspar #cj x #b #fj ,flint #ej x #b #ajj --- #cfb ,these ingredients are weighed out in double quantity to guard against loss in melting and are fused either in the kiln or in a special furnace4 ,a good fritting furnace is the ,no4 #ae1 made by the ,buffalo ,dental ,manufacturing ,company4 ,the charge is put into a plumbago crucible and when melted is poured out into water4 ,this breaks up the fritt and renders it easy to grind4 ,a similar crucible may be used in the kiln but as the fritt becomes very hard when cold and a crucible must be broken each time1 the furnace method is better4 ,if the fritt as given prove too sluggish to pour freely1 the feldspar may be omitted1 being added1 of course1 to the glaze mix4 ,the melted weight of the fritt must now be calculated4 ,borax contains in each equivalent #ahj parts water4 ,whiting contains in each equivalent #dd parts carbonic acid4 ,both water and carbonic acid pass off in the melting1 thus the #gf parts of borax will be reduced in weight to #dj parts1 and the #be parts of whiting will be reduced to #ad parts4 ,spar and flint undergo no loss4 ,the fritt after melting will therefore be3 ,borax #dj ,whiting #ad ,spar #cj ,flint #ej --- #acd ,and the final mix for the glaze will be3 ,fritt #acd parts ,white ,lead #gg ,zinc ,oxide #ab ,feldspar #bf ,kaolin #ac ,flint #fg ,this is ground on the mill as already directed and is ready for use4 ,fritted glazes are better than raw glazes for certain classes of ware4 ,they are usually whiter and less easily scratched4 ,they are1 moreover1 better for use with underglaze colors and are1 as a rule1 more easily melted4 ,it is never necessary to make a fritt for the preparation of matt glazes4 ,,part ,,iv3 ,,recipes ,while the purpose of this work is not so much to put ready-made materials into the hands of the craftsman as to enable him to work out his own plans1 it is recognized that there are some workers who lack the training and even the patience to do this4 ,for these1 the following recipes are given1 but with the proviso that no recipe can be regarded as perfect for all conditions4 ,just as an untrained cook can spoil a dinner even when surrounded by cookery books1 so the best of recipes will fail when unskillfully treated4 ,one must be prepared to recognize the faults which are sure to develop and to correct them in an intelligent manner4 ,the previous chapters should therefore be carefully studied1 not alone for the information but because the joy of the working depends greatly upon the knowledge one has of the operations involved and a modest confidence in one's own powers4 #a4 ,bright raw glaze4 ,cone 4#jf ,formula ,pb,o 4#fj ,ca,o 4#be ,al#b,o#c 4#ae ,si,o#b #a4de ,k#b,o 4#ae ,mix3 ,white ,lead #aee ,whiting #be ,feldspar #ee4g ,kaolin #ac ,flint #de ,grind1 with one-half pint of water1 for one hour4 #b4 ,bright raw glaze4 ,cone #a ,formula ,pb,o 4#de ,zn,o 4#ae ,al#b,o#c 4#bj ,si,o#b #a4fj ,ca,o 4#be ,k#b,o 4#ae ,mix3 ,white ,lead #aaf ,whiting #be ,zinc ,oxide #ab ,feldspar #hc ,kaolin #ac ,flint #cf #c4 ,bright fritted glaze4 ,cone 4#jb ,formula ,pb,o 4#be ,zn,o 4#ae ,al#b,o#c 4#ae ,ca,o 4#cj ,si,o#b #b4ce ,na#b,o 4#bj ,b#b,o#c 4#cj ,k#b,o 4#aj ,mix3 ,fritt ,glaze ,borax #aad ,fritt #aag ,whiting #fj ,white ,lead #fd ,soda ,ash #aj ,zinc ,oxide #ab ,spar #ef ,spar #bh ,flint #gh ,kaolin #ac ,flint #fj ,grind as before4 #d4 ,matt glaze4 ,cone 4#jb ,formula ,pb,o 4#ej ,ca,o 4#cj ,al#b,o#c 4#cd ,si,o#b #a4dh ,k#b,o 4#bj ,mix3 ,white ,lead #abi ,whiting #cj ,spar #aaa ,calcined ,kaolin #bb ,kaolin #aa #e4 ,matt glaze4 ,cone #g ,formula ,ca,o 4#ge ,al#b,o#c 4#ee ,si,o#b #b4aj ,k#b,o 4#be ,mix3 ,feldspar #aci ,whiting #ge ,calcined ,kaolin #ee ,kaolin #ac ,for colored glazes add to any of the above3 ,blue3 ,cobalt ,oxide #c parts ,slate blue3 ,cobalt ,oxide #c parts ,nickel ,oxide #a part ,warm blue3 ,cobalt ,oxide #b parts ,iron ,oxide #a part ,green3 ,copper ,oxide #h parts ,blue green3 ,copper ,oxide #h parts ,cobalt ,oxide #a part ,cool green3 ,copper ,oxide #h parts ,cobalt ,oxide #a part ,nickel ,oxide #b parts ,olive green3 ,copper ,oxide #f parts ,iron ,oxide #d parts ,orange brown3 ,iron ,oxide #h parts ,red brown3 ,iron ,oxide #h parts ,chrome ,oxide #a part ,zinc ,oxide #c parts ,yellow3 ,uranium ,oxide #c parts ,the coloring oxides should be weighed out and ground with the glaze4 ,any of the colors may be mixed together in order to modify the hue obtained or the amount of each coloring oxide may be varied to give a stronger or weaker value4 ,opaque tin enamel4 ,cone 4#jb ,formula ,pb,o 4#dj ,ca,o 4#be ,si,o#b #a4ge ,k#b,o 4#bj ,al#b,o#c 4#be ,sn,o#b 4#cj ,zn,o 4#ae ,mixture3 ,white ,lead #ajc ,whiting #be ,feldspar #aaa ,zinc ,oxide #ab ,kaolin #ac ,flint #bg ,tin ,oxide #de ,grind1 with one-half pint of water1 for #de minutes4 ,,part ,v3 ,,the ,,defects ,,of ,,glazes ,while it may chance that body and glaze and fire are so adjusted that faults do not develop1 this state of things is rare4 ,besides1 it is always possible that an occasional trouble may arise1 hence it will be well to recount a few of the commonest defects with the method of cure4 ,a cure is not necessarily specific4 ,there may be a complication of causes but the remedy indicates the line along which relief will be found4 #a4 ,crazing4 ,fine cracks appear in the glaze but do not penetrate the body4 ,there are many causes4 ,the body may be underfired or overfired4 ,in the former case the crazing does not always appear at once and it grows worse upon standing4 ,in the latter case the glaze is found to be crazed when taken from the kiln and it does not extend even after long standing4 ,the glaze may be underfired4 ,in this case the lines of the crack are broken and irregular1 one often changing its direction without meeting another crack4 ,in all these cases the remedy is obvious4 ,crazing also occurs when both body and glaze are correctly fired but there is an inherent disagreement in expansion4 ,in such a case a little flint added either to the body or to the glaze will tend to cure the trouble but it must be remembered that the addition of flint to the glaze is apt to render it less fusible and therefore while one craze may be cured another may be caused4 ,the addition of flint to the body is the simplest remedy4 #b4 ,shivering or peeling4 ,this is the reverse of crazing and is caused by the glaze being too large for the body4 ,it almost always appears immediately the ware is cooled4 ,the symptoms are that edges or convex surfaces are pushed off and even the ware itself is shattered4 ,the remedy is to decrease the flint in either body or glaze4 #c4 ,blistering4 ,glazes1 both bright and matt1 are apt to develop blisters at times4 ,these may be yet unbroken when the kiln is opened or they may have melted down to a small crater1 a ring with a depression in the center4 ,the cause of this fault is usually to be found in the body4 ,all clays contain sulphur and when a clay is aged this develops an acid which rises to the surface of the ware when dried and causes a scum4 ,the glaze attacks this sulphate scum and a gas is generated which boils out and causes the blisters4 ,if old clay blisters and new clay does not it may be regarded as certain that this is the cause4 ,a little barium carbonate added to the clay will help to effect a cure4 ,about one per cent4 is usually enough4 ,clay so treated1 however1 must not be used in plaster molds as the barium attacks the plaster4 ,if the cause be not found in the clay it may exist in the glaze itself4 ,some glaze ingredients contain impurities in the form of sulphates and these will cause blisters4 #d4 ,the glaze flows1 leaving bare places4 ,it is too fluid1 add a little clay and flint4 #e4 ,a matt glaze burns to a bright surface4 ,matt glazes must be used in a very thick coat4 ,if too thin they will inevitably brighten4 ,the fire may be too high4 ,the fire may be reducing1 that is1 with insufficient air4 #f4 ,the glaze crawls or rolls up in lumps4 ,notice whether the glaze is cracked before burning4 ,if so it will surely crawl4 ,too fine grinding is usually the cause of this trouble4 ,too much clay in the glaze may cause it1 or a too porous body4 ,a body which is underfired will almost certainly cause the glaze to crawl4 #g4 ,pinholes appear in the glaze when cool4 ,too rapid cooling is the cause4 ,,part ,,vi3 ,,alkaline ,,glazes ,the glory of the ,persian and ,egyptian blue is too alluring for potters to withstand4 ,though the pursuit of this glory leads one into all kinds of disasters and failures1 the avenues of research that it opens add unending fascination to the study4 ,even one beautiful glowing pot out of twenty or more efforts is a stimulating achievement though it should not be thought that this is the usual proportion4 ,it is a continual source of astonishment that with a slight variation of glaze formula a positive green will swim into a vibrating blue4 ,the addition or substitution of one substance or another in the glaze mix may be the key to an unexpected transformation and may give the potter a new palette of color4 ,the clay body has a very positive effect on alkaline glaze both in its composition and its color4 ,this is especially true under a transparent glaze where the effect is considerable since the color of the glaze would be modified by the red or buff clay showing through4 ,if1 therefore1 the object of the potter is to obtain a brilliant ,persian blue1 a white clay body must be composed or a white engobe applied over the buff or red clay to hide the color4 ,the ,persians and ,egyptians used a coarse1 sandy body high in silica and covered the roughness of the clay with a fine white engobe on which they painted their decorations in various colors4 ,the whole was finally covered with the transparent alkaline glaze4 ,while the effect of colored clay under opaque glaze is less pronounced1 it still makes sufficient difference to be considered4 ,the word engobe is ,french and refers to a thin coating of clay1 also called a slip1 laid over a colored body to change the color or over a coarse body to give a finer texture4 ,the engobe is usually composed of china clay1 flint1 and feldspar much as a white earthenware body is constituted but with a larger content of flint4 ,ball clay may also be used but the color is not so white4 ,the mixture of porcelain given on page forty will make an engobe suitable for many clay bodies4 ,if it should crack on drying more flint should be added4 ,an engobe must1 of course1 be put upon the unburned or green clay ware and this should be leather hard1 not dry4 ,the body with the engobe may be burned before glazing or the glaze may be put upon the unburned ware and the whole subjected to one fire only4 ,the ingredients in alkaline glazes are soda-ash1 whiting1 feldspar1 flint and oxide of tin4 ,the following is an example of a fritted glaze3 ,na#b,o 4#fj ,k#b,o 4#aj ,al#b,o#c 4#aj ,si,o#b #a4cj ,ca,o 4#cj ,soda ,ash #fd ,whiting #cj ,feldspar #ef ,flint #db ,the entire batch is fritted and ground in a ball mill with the usual amount of water for fritt grinding1 adding a tablespoonful of gum tragacanth mucilage to the batch after it is sieved4 ,the glaze should be the consistency of heavy cream when used4 ,it is also possible to use an alkaline glaze in the raw or unfritted state4 ,this necessitates grinding by hand in a mortar1 but great care must be taken to mix the dry ingredients thoroughly before adding water and to stir the glaze constantly while pouring in the water1 otherwise the soda-ash will cake and harden and be very difficult to break up4 ,a batch of glaze can be ground by hand in fifteen or twenty minutes if done vigorously4 ,it is then put through a #abj-mesh sieve4 ,the consistency is of importance4 ,if too much water has been added and the glaze has become thin1 it cannot be used successfully and should be discarded4 ,unfritted alkaline glaze does not keep well when moist but the ingredients can be ground dry and kept ready to be moistened as needed4 ,the following is an example of an unfritted alkaline glaze3 ,na#b,o 4#ei ,ca,o 4#ba ,al#b,o#c 4#bj ,si,o#b #a4f ,k#b,o 4#bj ,soda ,ash #fb ,whiting #ba ,feldspar #aaa ,flint #bd ,for color add the following oxides to a batch4 #a4 ,egyptian blue1 opaque--from #e to #h grams of black oxide of copper--#af grams of oxide of tin4 #b4 ,persian blue1 opaque--from #h to #aj grams of black oxide of copper--#af grams of oxide of tin4 #c4 ,sapphire blue--#a gram black oxide of cobalt4 #d4 ,aubergine--#i grams black oxide of manganese4 ,the clear glaze without any coloring oxide can be used over any of the colored glazes4 ,this is sometimes necessary when the colored glaze contains such a large proportion of coloring oxide as to show black on the surface4 ,the application of alkaline glaze is very important4 ,any of the three methods of pouring1 dipping1 and brushing can be employed4 ,brushing seems to give the best results but the glaze must be put on thick1 in two or three coats1 to give quality4 ,the firing is interesting and important because of the varied effects it develops from the same formula4 ,the range of temperature is great1 varying from cone 4#je to #a1 developing the alkaline glaze according to the result desired4 ,if the biscuit is soft fired the color will be more intense2 if hard fired1 the color will be much lighter in value with a high sheen on the surface4 ,an unfritted alkaline glaze burned to 4#je develops a soft matt finish4 ,where the color of a transparent ,persian blue comes out olive green1 too little glaze has been used on the piece or the buff of the clay has modified the color4 ,bubbles mean undeveloped glaze or sulphur in the clay or fuel4 ,black scum shows an excess of copper in the batch1 or reduction in the fire4 ,sand paper surface proves too low firing or too thin a glaze4 ,if one desires to reproduce the underglaze ,persian decoration the black outlines may be drawn with a black underglaze color mixed with clay4 ,a little mucilage must be added to secure smooth working4 ,the turquoise blue is copper oxide1 the dark blue cobalt1 and the purple manganese4 ,the oxides must be diluted with white clay and used rather thin4 ,the ,rhodian red is a finely ground red burning clay mixed with a little flint4 ,this red must be laid on quite thickly4 ,it will probably be found necessary to fire the painted decoration to about cone 4#jc before glazing4 ,the glaze may be either quite clear or slightly tinted4 ,another effect may be produced by using the black outline alone under a peacock blue or turquoise glaze4 ,a great many modifications and additions to this subject will suggest themselves to the potter as he works1 and a continual study of the masterpieces of the ,persians in the museums will prove the greatest inspiration4 ,,chapter ,,xvi3 ,,decoration ,the necessity for some kind of decoration upon the clay will always be a point of difference amongst artists4 ,some prefer the simple form with a glaze treatment only1 others consider that the surface should be broken up by design4 ,the question will not be debated here4 ,the aim of this hand-book is instruction and the individuality of the worker is to be encouraged4 ,directions for executing the different treatments do not imply that these elaborations are advocated4 ,that must be left to the inspiration of the worker4 ,decorations may be applied upon the soft clay by incising1 inlaying and embossing2 upon the dry clay or upon the burned pottery in color under the glaze or with no glaze at all2 in the glaze by the use of colors or colored glazes2 or over the glaze with colors and enamels4 ,each of these methods possesses special features4 ,each has its own possibilities and limitations and these should be mastered by the craftsman4 ,as in the production of form a well-planned design should be prepared4 ,the first sketch should be made on paper or on a slab of clay but the fitting and final arrangement are best made on the piece itself4 ,incising consists in the excavation of a shallow trench or trough on the surface of the clay4 ,the vase or jar having been finished should be kept in a damp place so that the clay does not dry out completely4 ,the design may be made in ,india ink with a brush4 ,a steel tool with a narrow chisel end is used for cutting and care must be taken that the clay is in such a condition of moisture as will admit of a clean trench being dug without any rough or broken edges4 ,the bottom of the trench need not be very smooth but the edges should be sharp and the lines well defined4 ,at the same time a mechanical hardness of finish is to be avoided4 ,the plastic nature of the clay should be kept in mind and every surface1 though decided in character1 should be soft and expressive4 ,this result can be secured by working over the cutting with a moist camel-hair brush4 ,the work must not be mopped so as to leave a woolly effect1 but a little sympathetic penciling will remove the hard lines of the tool4 ,there are two possible developments of incised work4 ,the details of the design may be excavated or the background may be cut out leaving the drawing in relief4 ,in modeling embossments the piece should be a little softer than for incising4 ,it is important that in any clay work attached to a clay body the same amount of moisture should be present in both parts4 ,this is not entirely possible in modeling upon forms which have already been shaped1 for if the form be as soft as modeling clay it will not bear to be handled1 while if the clay were as hard as the form it could not be worked4 ,a compromise is therefore necessary4 ,the vase must be kept as soft as possible consistent with holding its shape and the clay must be as stiff as the working will allow4 ,as little water as possible should be used and the modeling should not be brought to its full height at once4 ,if the clay be laid on little by little there is much less chance of cracking4 ,low relief is sometimes produced by painting in slip but here even more care is necessary4 ,the slip should be laid on with a brush in thin coats1 each coat being allowed to stiffen before another is applied and the whole work being kept moist4 ,an atomizer with clean water is useful in this regard4 ,the work1 being kept on a whirler or turntable1 is sprayed now and then with water and thus prevented from becoming too hard4 ,when the slip work has been raised to the desired height the surface is tooled over so as to remove the brush marks4 ,this is the method which has been brought to such perfection by the ,french artists and by them named pte-sur-pte4 ,modeled work is generally carried out in the same clay as that of which the form is made and depends upon high relief for its effect4 ,slip painting is usually done in a different color and if a light-colored slip be used upon a dark clay1 the latter is partially seen through the coating in the thinnest places4 ,this fact is made use of to accentuate the shadow effects4 ,in using one clay over another great care must be taken to insure that the fire shrinkage is the same4 ,the white body already given1 or indeed1 any light colored clay1 may be tinted by the addition of under-glaze colors4 ,the dry color1 if sifted very fine1 may be added to the plastic clay by thorough kneading and wedging but it is better to work up the clay into a slip and to stir in the color4 ,the tinted slip is then lawned two or three times and dried out on plaster or used in the slip state as the case may be4 ,a trial should be made before any important work is undertaken1 both to see that the color is right and to discover any discrepancy in shrinkage4 ,if a clay shrinks too much1 a little ground flint may be added4 ,if it shrinks too little1 a little ball clay will correct it4 ,the tint produced by the color is apt to darken in the kiln but the general hue will be similar to that of the color used4 ,for some classes of work a native red clay gives admirable results4 ,it may be lightened by the use of kaolin and flint and darkened by adding burnt umber4 ,these colors are more satisfactory than greens and blues in clay because the brown and red tones are natural1 the others are artificial4 ,if a good buff-burning clay be available1 it forms the best possible foundation for color work4 ,burnt umber will darken it and red clay may be mixed with it1 always having regard to the matter of shrinkage already mentioned4 ,very pleasing effects may be produced by inlaying one clay with another4 ,the pattern or design is first cut out as described under incising and then the second clay is pressed1 morsel by morsel1 into the excavation4 ,the surface is cleaned off level with the body of the piece and the whole may be either polished or glazed4 ,a plastic clay can be polished when leather hard and the finish will remain after firing4 ,any tool of steel1 boxwood or ivory will do the work but a good supply of patience is needed so that the whole surface may be uniformly treated4 ,for color decoration upon the pottery1 ordinary underglaze colors are used1 either upon the unburned clay or upon the burned ware commonly called biscuit4 ,for use upon the clay1 the colors should be mixed in water1 using a little molasses1 sugar1 glycerine or gum arabic to make the color flow easily from the brush4 ,before burning1 a little glaze should be sprayed over the work with an atomizer4 ,any ordinary fusible glaze will do4 ,it is diluted with a good deal of water as only the very thinnest coat is necessary4 ,the spray should not be held long in one place or the water will flow and smear the color4 ,if the piece be turned slowly around the clay will absorb the water as it is applied4 ,if this spraying be not done the colors will be apt to rub off after burning4 ,under-glaze colors are not fusible and hence they come from the fire as dry powders4 ,the work on the biscuit is much the same except that turpentine and fat oil constitute a better working medium4 ,when dry the spray should be applied as before4 ,,chapter ,,xvii3 ,,the ,,fire ,kilns and burning form the pivot upon which the art of the potter turns4 ,m4 ,doat has said1 ,a potter can no more express himself without his kiln than can a violinist without his violin1 and yet there are some who try to make out by sending their work to some nearby pottery to be burned4 ,let it be at once understood that he who finds it impossible to procure and manage a kiln had best take to some other craft4 ,kilns are of two types1 open and muffle4 ,in the open kiln the flames pass through the firing chamber and the ware may be exposed to their action1 as in stoneware and brick2 or it may be enclosed in the fire-clay cases1 called saggers1 as in the many forms of pottery1 dishes or faience4 ,the muffle kiln is a closed chamber which is surrounded by flames but which is not entered by them4 ,these kilns are used in the manufacture of terra cotta and heavy enamel wares1 and the portable kilns made for studio use are of this type4 ,there are certain advantages to be gained in the use of either type of kiln but inasmuch as the open kiln involves the use of saggers and as1 moreover1 it must be properly constructed of fire-brick by a skilled mason1 it will be best to consider only the portable studio kiln4,m ,m ,these kilns are made in several sizes by the ,h4 ,j4 ,caulkins ,company1 ,detroit1 ,mich4 ,it must not be expected that any kiln will give perfect satisfaction4 ,neither built kiln nor portable kiln will do this1 but either may be relied upon to do excellent work in the hands of those who will take trouble4 ,a kiln of the proper size having been purchased1 it must be carefully installed4 ,a good chimney is an absolute necessity and if one can be built on purpose it will be best4 ,it should be at least twenty-five feet high with the bottom lined with fire-brick to a height of six or eight feet4 ,the portable kiln is set on iron legs which raise it about one foot from the floor4 ,this is not enough for easy work and a platform of brick or stone1 ten inches high1 should be prepared4 ,this will greatly simplify the observation and management of the burners which are beneath the kiln1 and if it should make the inside of the muffle hard to reach1 it is easier to stand on a box to attend to the kiln than it is to go on one's knees to the burner4 ,the kiln room should have a cement floor and should be both well drained and well ventilated4 ,at the window there should be a stout bench where the work of preparation may be done and at a convenient spot there should be shelves for stilts1 cones1 wash1 stopping and all the minor accessories of burning4 ,if there is room for a barrel of oil it will be a convenience1 and if the room be fire-proof the insurance company will not object4 ,the kiln having arrived it is mounted on the platform and the asbestos-lined pipe is securely connected with the chimney4 ,the inside of the muffle is examined with care to see that no part has been jarred in transit4 ,the reservoir cans are filled with oil and a slow fire is started4 ,this should be allowed to burn very gently for an hour or two in order to thoroughly dry out and season the kiln4 ,it is a good plan to make up a wash of equal parts of kaolin and flint and to brush this all over the inside of the kiln4 ,it should not be put on so thick as to shell off from the walls but at the bottom a good coating may be laid4 ,this protects the walls of the kiln from the attacks of glaze and will make them last longer4 ,in order to fill the kiln economically a number of props and bats must be provided4 ,some of these are sent out with the kiln but one is always needing odd sizes and extra pieces4 ,the props are simply legs of burned clay2 they are of any height desired and should be thick enough to stand alone4 ,the bats are slabs of burned clay and they rest on the props to form shelves4 ,the bats must be thick enough to bear the weight of any pieces which they may be called upon to support1 but they need not be very large as two or more may be used to bridge the width and length of the kiln4 ,bats and props are best made of sagger clay to which has been added about one-third of crushed fire-brick4 ,broken bats serve well for this after the first supply has been secured4 ,this crushed burned clay1 called grog1 has a very important influence upon wares which have to be heated again and again4 ,the size used should be about what will pass through a #af-mesh sieve1 and if the dust be sifted out through a #dh-mesh sieve1 the resulting ware will be stronger4 ,that is1 only the grog which passes a #af sieve but lies upon a #dh sieve should be used4 ,the relative proportions of clay and grog in the mix will depend somewhat upon the nature of the clay4 ,three parts of clay to two of grog by measure will be about right4 ,the first charging of the kiln should be with pieces of no great importance4 ,the temperature in different parts must be carefully ascertained4 ,in order to do this a number of pyrometric cones,n are prepared in groups of three4 ,n ,the pyrometric cones are fusible pyramids for testing heat4 ,they are made by ,prof4 ,edward ,orton1 ,jr41 ,columbus1 ,ohio4 ,let us suppose that the work is intended to be carried out at a temperature of ,cone ,no4 #ja4 ,the numbers run both ways from this4 ,the higher or less fusible cones are1 #a1 #b1 #c1 #d1 etc41 up to #cf1 and the more fusible numbers are #jb1 #jc1 etc41 down to #jbb4 ,if the firing is to be to ,cone #ja1 numbers #jb1 #ja and #a are selected and set upright in a small strip of soft clay4 ,eight or ten of these groups of three cones are to be prepared for the first firing1 so as to test the kiln1 one group is placed in each corner1 at the bottom1 and another in each corner on a shelf1 which is arranged opposite the spy-hole in the door4 ,in the middle of this1 where it can be well seen through the hole1 one of the groups of cones is placed4 ,they must be set so that all three cones are visible as the kiln is being fired4 ,the kiln is now filled up on both levels with pieces of pottery4 ,to burn an empty kiln is not a reliable test4 ,on the first occasion the fire should be started in the morning because no one can tell just how long the burn will take4 ,when this time is ascertained it is best to start the fire so that the kiln will be finished by early evening4 ,the cooling then takes place at night and there is no temptation to open the door too soon4 ,the fire is started slowly and the flow of oil is gradually increased as the muffle begins to glow4 ,the work here needs practice1 nerve and judgment4 ,a good deal of smoke will be seen at the chimney at first but this should disappear as the kiln grows red4 ,if the fire be urged too strongly at the beginning fuel will be consumed to no purpose1 the only result being the choking of the flues with carbon4 ,as the red becomes visible through the spy-hole1 more oil may be supplied1 but notice must be taken that the smoke at the chimney does not increase4 ,the ideal firing is where there is no smoke but this cannot be reached until the kiln is hot enough to cause the smoke to burn4 ,persons who have burned kilns for overglaze work will find the method of burning pottery very different4 ,instead of a fire brought as rapidly as possible to the finishing point1 there must now be a slow soaking burn in which the heat shall have time to saturate the ware4 ,the cones in front of the spy-hole must be observed from time to time and presently as the kiln reaches a bright cherry red1 number #jb will begin to bend at the tip and will gradually arch over until the point touches the shelf upon which the cones stand4 ,by this time number #ja will have begun to bend and when the point of this has touched the shelf1 the firing is over and the oil is shut off4 ,it requires some resolution to leave a kiln until morning but it is conducive to early rising anyway4 ,the kiln need not be quite cold but it will help the kiln itself to wear better and the pottery will be better if nothing is done until everything can be handled without gloves4 ,the cones are now taken out and a diagram is made of each level with the bend of each cone accurately drawn4 ,this diagram should be mounted and hung on the wall for reference4 ,it is not well to trust to memory4 ,it will probably be found1 in the type of kiln we are discussing1 that the cones on the bottom have bent further than those on the shelf4 ,that is1 the bottom is somewhat the hotter4 ,the variation in the kiln is not necessarily a disadvantage4 ,it may be utilized in burning wares of different kinds4 ,for example1 if the bottom prove much the hotter1 the biscuit ware may be placed below and the glazed pieces on the shelf4 ,in such case the shelf itself should be washed with a good coating of clay and flint in order to protect it from casual drops of glaze4 ,if a number of small pieces are being made1 more than one shelf should be set up4 ,the legs may be just a little taller than the tallest of the small pieces1 but the art of placing or filling a kiln economically consists in making selection of pieces which fit well together both as regards height and shape4 ,thus1 pieces which are large at the base may be dovetailed in with others of which the base is smaller than the upper part4 ,in the case of clay ware the pieces may be set close together or even piled one upon another4 ,there is no danger of sticking unless the ware is burned to complete vitrification4 ,the glazed pieces must not1 of course1 touch each other4 ,it will be seen1 from these instructions1 that there should be a good assortment of wares from which to select4 ,economical firing cannot be managed if a burn be attempted whenever a piece is ready1 and patience must be exercised so as to fill the kiln to advantage4 ,it is important that anyone attempting to burn a kiln should have some understanding of the phenomena of combustion4 ,many things occur in the firing which1 without such an understanding1 are not easily explained but which become perfectly clear when considered in the light of simple chemical science4 ,combustion means oxidation or a combination between the elements of the fuel1 principally carbon and hydrogen1 and the oxygen of the air4 ,this combination is a chemical action and as it proceeds heat is liberated4 ,with a given amount of a specific fuel and a given amount of air there is always the same amount of heat1 but the rate at which this heat is given off varies with the time occupied in the operation4 ,heat may be generated slowly which means a low temperature1 or the same volume of heat may be generated rapidly1 occupying a much shorter time and developing a higher temperature4 ,from these statements it will be seen that there is a difference between heat and temperature2 heat means volume1 temperature means intensity4 ,thus the temperature derivable from a given amount of fuel depends upon the rapidity with which it is burned4 ,combustion may be either complete or incomplete4 ,in the former case enough air is supplied to oxidize all the fuel with1 usually1 some excess4 ,the contents of the kiln are then bathed in the heated oxygen and the condition of the burning is called oxidizing4 ,when the combustion is incomplete1 on the other hand1 there is a deficiency of oxygen4 ,the kiln is charged with hot carbonaceous gases and smoke1 and these1 being hungry for oxygen1 will abstract it from any substance which may be present4 ,this condition is called reducing because the compounds which exist in clay or glaze are deprived of oxygen and thus reduced to a lower state of oxidation4 ,in burning a kiln one should be able to produce either of these conditions at will because there are certain wares which require one or the other in order to secure the best results4 ,to put the matter in a nutshell1 oxidizing conditions are induced by a strong draft and open flues1 reducing conditions are obtained by closing the air inlets and using a liberal amount of fuel4 ,,chapter ,,xviii3 ,,high-,,temperature ,,wares ,the subject of ,grand ,feu ,ceramics has been so ably developed by ,m4 ,taxile ,doat in his admirable treatise,p that it will be unnecessary to go deeply into the matter1 but in order that the reader may be aware of what is involved1 some description of the technique will be given4 ,p ,keramic ,studio ,publishing ,co41 ,syracuse1 ,n4 ,y4 ,hard-fired wares are divided into two classes1 porcelain and stoneware4 ,the latter is called by the ,french1 ,grs1 an abbreviation of the name ,grs de ,flandres1 the stoneware made in the low countries in the sixteenth century4 ,both these wares are1 technically1 once fired1 that is1 the body and glaze come to maturity at one and the same burning4 ,the biscuit ware is often given a low burn at first in order to facilitate handling1 but this leaves the body very porous and is in no sense a maturing fire4 ,the glaze is laid upon this porous ware1 or upon the unburned clay if preferred1 and then comes the high fire or ,grand ,feu of the ,french4 ,a mix for a porcelain body has already been given but if the ceramist means seriously to attack the porcelain problem he will have to do some experimental work for himself4 ,the ,georgia kaolin mentioned in the recipe on page #dj is a good1 plastic clay but it is slightly off color4 ,it may be necessary to improve the color by the use1 in part1 of another kaolin such as the ,harris clay from ,north ,carolina4,q ,q ,the ,harris ,kaolin ,company1 ,dillsboro1 ,n4 ,c4 ,furthermore1 in the preparation of a fine porcelain it is necessary to grind the whole mix upon a mill4 ,the mill used for glaze grinding will answer every purpose and care must be taken that the grinding1 while carried far enough1 be not too long continued4 ,a certain amount of fine grit in the body mass is necessary but only by constant practice can the right point be reached4 ,in making these experiments each step should be faithfully noted in a handy book4 ,the amount of water to a given weight of clay and the duration of the grinding should be accurately observed and written down4 ,it is most unwise to trust to memory4 ,the process of casting may be used for porcelain as already described1 but the very best of workmanship is necessary4 ,the hard fire to which the porcelain is subjected reveals every error which has occurred in the making4 ,the same thing applies to wheel work4 ,not only is great skill required in order to shape the tender porcelain clay on the wheel but the very essence of the porcelain is its lightness1 to produce which by craftsmanship a long and arduous course of training must be endured4 ,stoneware is free from many of these difficulties and1 consequently one who attempts the conquest of high-temperature wares is advised to begin with this4 ,stoneware clay need not be a mixture4 ,there are many clays which can be used for the manufacture of grs with no more preparation than that laid down for common clays4,r ,it sometimes happens that a clay will need the addition of a small quantity of flint or spar but this does not amount to a difficulty4 ,r ,stoneware clays may be procured from ,the ,western ,stoneware ,company1 ,monmouth1 ,ill42 ,h4 ,c4 ,perrine and ,sons1 ,south ,amboy1 ,n4 ,j4 ,stoneware does not present the same manufacturing difficulties as are found in porcelain4 ,the clay is quite plastic and can be easily shaped on the wheel2 casting is scarcely a suitable process for this ware4 ,the essence of stoneware is strength and virility1 just as that of porcelain is lightness and grace4 ,each ware has forms suited to itself and it is a mistake to depart from these essential characteristics4 ,after shaping and drying the technical manipulation of both wares proceeds along the usual lines4 ,the first fire is at a very low temperature4 ,the melting point of silver 7cone #jaj7 is enough in nearly every case4 ,this leaves the ware in a soft and porous condition but hard enough to resist the action of water4 ,the process of glazing has already been described but the composition of the proper glazes differs from that of low temperature glazes4 ,porcelain is always burned in a reducing fire2 stoneware may be burned either reducing or oxidizing4 ,the temperature at which the glaze is burned is very high1 it must be1 in fact1 the maturing point of the body itself4 ,the simplest form of porcelain glaze is that represented by the formula-- ,k#b,o 4#c ,ca,o 4#g ,al#b,o#c 4#e ,si,o#b #d4j ,which is carried out in the following mixture3 ,feldspar #afg ,whiting #gj ,kaolin #eb ,flint #ajh ---- ,the glaze is ground for use4 ,the same glaze will also serve for stoneware but it will burn to a brilliant surface whereas stoneware is better when finished with a matt texture4 ,the following is a stoneware matt glaze3 ,k#b,o 4#c ,ca,o 4#g ,al#b,o#c 4#g ,si,o#b #b4f ,of which formula the mixture is-- ,feldspar #afg ,whiting #gj ,calcined ,kaolin #ff ,raw ,kaolin #bf ---- ,the porcelain glaze is at its best when uncolored4 ,the matt glaze will be more interesting when used as a colored coating4 ,the following are a few suggestions for colored matt stoneware glazes4 ,to the glaze batch1 #cbi parts1 add3 ,for blue3 ,cobalt ,oxide #b parts ,nickel ,oxide #a part ,ground ,rutile #aj parts ,for brown3 ,iron ,oxide #f parts ,nickel ,oxide #c parts ,ground ,rutile #aj parts ,for green3 ,chrome ,oxide #b parts ,cobalt ,oxide #a part ,iron ,oxide #d parts ,for dark red3 ,iron ,oxide #aj parts ,chrome ,oxide #b parts ,zinc ,oxide #f parts ,rutile has not before been mentioned4 ,it is a crude oxide of titanium and is exceedingly useful in high temperature work for producing odd1 mossy and crystalline effects4 ,these mixtures make no pretense to be complete1 they are given as suggestions only because if the artist-potter is to be successful he must be prepared to compound glazes which are the expression of his own individuality4 ,for burning high-temperature wares the kilns already described may be used but upon purchasing it should be stipulated that the kiln is to stand burning up to cone #aa or #ab4 ,successful porcelain can be made at cone #aj but better results are secured at cone #ab1 though1 of course1 the wear upon the kiln is proportionately greater4 ,stoneware requires a burn of about cone #i1 higher or lower according to the clay used but fine results must not be expected below cone #g nor is it necessary to go higher than cone #aj4 ,,chapter ,,xix3 ,,clay-,,working ,,for ,,children ,one of the modern developments of clay-working is the use of it in elementary and high schools as a branch of manual training4 ,in this1 clay meets the most exacting needs of the work for it affords a perfect means of self-expression4 ,other arts interpose between the pupil and his material a series of tools or appliances1 more or less elaborate1 which constitute a barrier to the personal touch4 ,clay presents no such obstacles4 ,the ten fingers are all the tools that are necessary at the beginning and1 consequently1 the personal equation in clay-working is remarkably high4 ,in the kindergarten the children take to clay work as little ducks to water and the interest is never lost4 ,in this way1 clay1 instead of adding to the labors of a teacher already overburdened by a plethora of subjects1 constitutes a real relief4 ,the work is so interesting that it moves along of itself and all that is needed is intelligent direction4 ,it is1 of course1 necessary that anyone attempting to teach clay-working to children should have a knowledge of methods and principles4 ,the essence of power1 especially in teaching1 is reserve1 but there is great danger in expecting too much from small heads and hands4 ,in the early exercises the skill of the teacher should even be employed to conceal her art4 ,it is a mistake to place before elementary pupils work which is far beyond their reach4 ,let the teacher make before the class something which they themselves can do if they try and they will be encouraged to greater effort4 ,a small cylinder is a suitable beginning exercise for several reasons4 ,the form is definite and the result may therefore be easily criticized by the children themselves1 the size of the piece may be readily adapted to the small fingers and the simplicity of line enables the attention to be concentrated upon the manipulation of the clay4 ,this cylindrical form may be made more interesting by the addition of little feet or handles2 by a simple line border incised along the upper edge2 or by dividing the surface into well-spaced panels4 ,the planning of the cylinder itself is a good exercise in rectangle proportion4 ,in order to enable the pupils to turn their work from side to side each one should be provided with a piece of paper or cardboard the size of the base of the pottery4 ,the building is started upon this and1 managed in such a way1 the clay does not stick to the table4 ,when the idea of pottery building1 either by coils or by pieces welded together1 has been grasped1 the children should be taught to think in the solid4 ,there is almost always a difficulty in making children see that an outline drawing and a solid form may be alike in meaning4 ,the teacher should draw upon the blackboard a simple jar in elevation1 the plan1 of course1 will be a circle4 ,the same thing is then made in clay by both teacher and children and the results are compared with the drawing4 ,this will lead to the designing of the forms in outline by the children themselves4 ,these designs should be made the exact size of the proposed pottery and if the outline be carefully cut out the line of the paper may be applied to the work as a template4 ,by such means the children are led to produce accurate lines in the clay and control over the material is secured4 ,there is always a temptation1 when the clay sags or loses shape1 to diverge from the original idea and to allow the material to shape itself4 ,this inevitably leads to slovenly work and should be resisted from the first4 ,the paper template helps to correct such an impulse and the pupil presently finds that the clay can be successfully controlled if enough trouble be taken4 ,there is much interest too in the cutting of pottery forms from folded paper4 ,a number of these forms may be pinned on a screen and the children led to select the best in line and proportion4 ,too much emphasis cannot be laid on the necessity for showing the children fine examples of pottery1 both ancient and modern4 ,the more primitive types1 where the form and the decoration are so perfectly adapted to each other and to the material1 are full of inspiration for the child potter as well as for the adult4 ,when one is fortunate enough to be near a museum1 many illustrations will be found1 but good photographs or drawings are available for almost everyone4 ,constant comparison and the exercise of choice will lead to a development of taste1 which must affect the child whether he later becomes a producer or a consumer4 ,a flower holder is a good problem4 ,it is a solid piece of clay two or three inches in diameter and an inch thick4 ,this may be round or square in form and may have simple modeled decoration added to it4 ,quarter inch holes are pierced at regular intervals1 in fact1 they themselves should form part of the design4 ,for the older children a shallow bowl of good line with a flower holder to fit is an interesting problem4 ,other good problems1 which may be made more or less difficult according to the grade in which they are given1 are rose jars1 bread and milk bowls1 incense burners1 cylindrical jars1 square fern dishes1 candlesticks and small lamp bases4 ,when working out decoration for pottery forms1 it is well to have the children make their designs with the modeling tool upon the clay itself4 ,if a piece of soft clay be rolled out flat upon the table it affords the best possible medium for making clay designs4 ,the pupil is at once put in touch with the possibilities and limitations of the material4 ,a drawing made upon paper may have to be entirely changed before it is suitable for use on clay4 ,the soft surface can be smoothed over as often as necessary and a new sketch made until a design is approved for application to the pottery itself4 ,in the chapter on decoration will be found suggestions for clay treatment4 ,the making of tiles affords an interesting application of the principles of design1 but the instructions in the chapter on tile should be followed in order to insure a workman-like product4 ,if it is possible to use plaster1 the making of a decorated tile from which a mold can be made and other tiles pressed is a good problem4 ,animal forms lend themselves to the decoration of such tiles and are always interesting to children4 ,while these chapters are especially devoted to ceramics in the sense of burned and glazed pottery a few words upon modeling as related to school work may be added here4 ,imitative modeling from cast or copy with its development of animal and figure modeling1 both from life and from memory1 is valuable in the acquirement of the power of manipulation and control as well as in the cultivation of observation1 imagination and memory4 ,in the best regulated schools the work of the grades is often correlated in the study of some phase of human life4 ,facts are grouped around some epoch or event in history or some country or clime in geography4 ,the children take up the clay while their minds are full of the current subject and nothing more natural than that they should illustrate the story by models4 ,such work is to be thoroughly commended as truly educational1 though it does not fall strictly within the field of pottery and a few suggestions may therefore be in order4 ,the modeling of animals or people for the sand table is full of interest for the younger children4 ,such stories as ,the ,three ,bears1 ,chicken ,little and ,the ,little ,red ,hen immediately suggest themselves4 ,for children of about the fourth grade ,alice in ,wonderland offers a most fascinating array of models4 ,the ,white ,rabbit1 ,the ,duchess1 ,the ,mock ,turtle1 ,the ,mad ,hatter1 grotesques of all sorts1 seem a natural outcome of this illustration work and the wise teacher will see the possibility for developing the imagination in the modeling of mythical creatures1 such as dragons and gnomes1 and in the personification of the elements4 ,there is also an unlimited fund of material in the tales of knighthood and of fairyland4 ,with the older children1 simple principles of design and composition should be suggested4 ,a paper weight is an interesting problem demanding the adaptation of form to space4 ,many of these things may be modeled in clay1 dried and painted with water color or one of the patent modeling clays which set like cement may be used4 ,if no supports have been left in the model it may be fired when thoroughly dry4 ,some of the best projects for sand table work involving modeling are ,eskimo ,life1 ,indian ,life1 ,farm ,life1 ,the ,circus1 and ,fairy ,tales4 ,generally a suggestion is all that is necessary to call forth the most original conceptions and once started the children will soon far outstrip the teacher4 ,,index ,a ,alhambra ,vase1 #af ,armenian ,bole1 #ae ,b ,ball-,clay1 ,tennessee1 #dj ,bases for ,glaze1 #adc ,berlin ,porcelain1 #bh ,bisilicate ,glaze1 #ade1 #adf ,black ,surfaced ,ware1 #ac ,blistering of ,glazes1 #aff ,building1 ,clay for1 #fi ,building1 ,faults in1 #gb ,building1 ,methods of1 #gj1 #ga ,built ,pottery1 #aj1 #fh ,burning ,tiles1 #aci ,c ,case for ,mold-making1 #eh ,casting1 #abi ,casting1 ,slip for1 #abi ,castor ,ware1 #ac ,children1 ,pottery for1 #aid ,chinese ,porcelain1 #bc ,clay1 ,colored1 #cf ,clay1 ,crude1 #i1 #cg ,clay1 ,decoration in1 #agc ,clay1 for ,building1 #fi ,clay1 for ,tiles1 #acd ,clay1 ,preparation of1 #cg ,colored ,glazes1 #bd1 #adc1 #afc ,colors1 ,underglaze1 #be1 #adc1 #agg ,combustion1 #ahf1 #ahg ,cones1 ,pyrometric1 #ahb ,copenhagen ,porcelain1 #bg ,crawling of ,glazes1 #aff ,crazing of ,glazes1 #afe ,cups and ,saucers1 #abd ,d ,decoration1 #agc ,decoration of ,tiles1 #acg ,defects of ,glazes1 #afd ,devitrification1 #aeb ,e ,earthenware1 ,mixture for1 #dj ,engobe ,ware1 ,oriental1 #ae ,f ,famille ,rose1 #bd1 #bf ,famille ,verte1 #bd1 #bf ,feet for ,vases1 #aje ,firing the ,kiln1 #agi ,fitness in ,design1 #c1 #d1 #g ,flowing of ,glazes1 #ade1 #aff ,form and ,weight1 #g ,fritt for ,glaze1 #aeh ,fritting ,furnace1 #aei ,g ,glaze1 ,bases for1 #adh ,glaze1 ,bisilicate1 #add1 #ade ,glaze1 ,calculation of1 #aej ,glaze1 ,fritt for1 #aeh ,glaze1 ,pinholes in1 #afg ,glaze1 ,porcelain1 #aia ,glaze1 ,recipes1 #afj ,glaze1 ,stoneware1 #aia1 #aib ,glazes1 ,blistering of1 #aff ,glazes1 ,clear1 #ada1 #afa ,glazes1 ,colored1 #adc1 #afc1 #aib ,glazes1 ,crawling of1 #aff ,glazes1 ,crazing of1 #afe ,glazes1 ,defects of1 #afd ,glazes1 ,flowing of1 #ade1 #aff ,glazes1 ,grinding1 #aea1 #aee ,glazes1 ,ingredients for1 #adb1 #adc ,glazes1 ,matt1 #aeb1 #aia ,glazes1 ,nature of1 #ada ,glazing1 #adj ,glazing ,tiles1 #acg1 #ach ,grs de ,flandres1 #ba ,gum ,tragacanth1 #aef ,h ,hard ,porcelain1 #bc1 #ahi ,high-temperature ,wares1 #ahh ,i ,ingredients for ,glazes1 #adb1 #adc ,j ,jars for ,storing ,clay1 #da ,k ,kiln1 ,firing the1 #agi ,kiln1 ,portable1 #ahj ,kilns1 #agi ,l ,lawns1 ,silk1 #da ,large ,pieces1 #ajg ,m ,matt ,glazes1 #aeb ,methods of ,making ,tiles1 #ace1 #acf ,molds for ,plates1 #fb1 #fc ,molds for ,vases1 #eb ,o ,oriental ,engobe ,ware1 #ae ,ox-blood ,red1 #bd1 #bf ,oxidizing ,fire1 #ahg ,oxygen ,ratio1 #ade ,p ,pte-sur-pte1 #ad1 #age ,pieces1 ,large1 #ajg ,pinholes in ,glaze1 #afg ,plaster-of-,paris1 #de ,plaster ,dishes1 #df1 #dg ,plaster ,head for ,wheel1 #fe1 #gh ,plaster1 ,setting of1 #de ,porcelain1 ,berlin1 #bh ,porcelain1 ,copenhagen1 #bg ,porcelain ,glaze1 #aia ,porcelain1 ,hard1 #bc1 #ahi ,porcelain1 ,mixture for1 #dj ,porcelain1 ,sevres1 #be ,potter's ,wheel1 #gd ,pottery1 ,built1 #i1 #fh ,pottery1 for ,children1 #aid ,pottery1 ,white-coated1 #ad1 #afh ,props and ,bats for ,kiln1 #ahb ,pyrometric ,cones1 #ahb ,r ,recipes for ,glazes1 #afj ,reducing ,fire1 #ahg ,s ,salt-glazing1 #ba ,saucers1 ,cups and1 #abd ,shivering of ,glazes1 #afe ,size1 ,mold-makers'1 #dd ,slip1 #ch1 #ci1 #abi ,slip for ,casting1 #abi ,slip-painting1 #age ,stoneware1 #ba1 #ahh1 #aij ,stoneware ,glaze1 #aia ,t ,tennessee ,ball-clay1 #dj ,tiles1 #acc ,tiles1 ,burning of1 #aci ,tiles1 ,clay for1 #acd ,tiles1 ,decoration of1 #acg ,tiles1 ,glazing1 #acg1 #ach ,throwing1 #gg ,tin ,enamel1 #afd ,tragacanth1 ,gum1 #aef ,turning ,tools1 #ajj ,u ,underglaze ,colors1 #adc1 #agg ,v ,vase ,forms1 ,turning1 #di-eb ,vases1 ,feet for1 #aje ,vases1 ,molds for1 #eb ,w ,weight and ,form1 #g ,white-coated ,pottery1 #ad1 #afh advertisement ,books for the ,craftsman ,we can always supply any book on the ,manual ,arts--whether it is issued by us or by any other publisher4 ,our stock of these books is complete and our facilities for filling your orders promptly and carefully are unsurpassed4 ,send your inquiries to us4 ,a request will bring our various catalogs4 ,d4 ,,van ,,nostrand ,,co41 ,,inc4 #h ,warren ,street ,new ,york ,city