Porcelain, a sketch of its nature, art and manufacture

Preface

THE interest of Porcelain is perennial, and though book succeeds book, the subject remains unexhausted. The aim of this little book is to supply the collector and student of Porcelain, as well as the general reader, with a clear and connected account of the various kinds of porcelain made in Asia and Europe. It has taken me more years than I like to count to arrive at the ideas set down in the following pages, and I hope that, as a result of my labours in sifting, weighing, selecting, and arranging, the knowledge gained from so many diverse sources, others may be saved a great deal of unnecessary trouble.

This is in no sense a technical treatise, yet it is based — on a practical experience in many branches of the Potter’s Art, which has, I trust, enabled me to exhibit certain aspects of the subject in a way that will be new to the bulk of my readers. Throughout the work I have been careful to explain how the artistic qualities of the various porcelains have been influenced by the nature of the materials and processes used in different countries ; the information being of such a character as will enable a collector to find the scientific explanation of the differences which an artist feels.

Many difficulties have to be faced in a work necessarily so compressed as this. In the first place, it is impossible to keep the treatment accurately in scale. Naturally, perhaps, in an English book the records of the English factories occupy more space than the artistic merit of their productions would warrant; while German porcelain makes so little appeal to our English tastes, that a German might, not unreasonably, complain that the factories of his country had received less attention than they deserve. Others may think that Japanese porcelain has been somewhat slighted, but I have honestly tried to give a picture that should represent as truly as possible, within the prescribed limits, the development of every important kind of porcelain known.

It is, perhaps, necessary to say a word in explanation of the attention given to the Letters of Pére d’Entrecolles. In the first place I think it would be impossible to over-

sbei iv PREFACE.

rate the importance of these letters, which first gave to the European potters of the eighteenth century such a vivid and detailed account of the manufacture of Chinese porcelain in the period of its culmination. The more we know about Chinese porcelain, the more there is to excite our astonishment that this Jesuit father, who was no potter, should have been able to observe and describe so faithfully what he saw at Ching-té-chén. There is no doubt, in my mind, that these letters of Pére d’Entrecolles suggested many of the things that have made certain European porcelains the distinctive wares they are.

' The question of the ‘‘marks’’ used on the various porcelains has exercised my mind a good deal, and after much doubt and perplexity, I have come to the conclusion that it would be better to omit them altogether from this book. In the first place, it would need a volume as large as this to discuss the subject of ‘‘ marks ’’ alone ; but far beyond that, I am convinced that most collectors have paid a great deal more attention to marks than they deserve ; and that the only safe method of discrimination must be based on the observation of the qualities of body and glaze, or colour and decoration, such as has been followed here. It must never be forgotten (1) that many of the choicest specimens of porcelain are unmarked ; (2) that the marks of one period or one factory have been imitated or copied at other times and places; and (3) that the first thing a forger imitates, and generally the easiest thing for him to imitate, is the mark of the much-prized ware. Bearing these facts in mind, as well as the fact that there are many volumes already in existence exclusively devoted to this branch of the subject, I have given no reproductions of marks in this volume, deeming it better to devote the space to more important things.

In conclusion, I have to thank Mr. Bernard Rackham, of the Victoria and Albert Museum, for much assistance in the selection of typical specimens for illustration ; and in the supervision of the photographer when it was impossible for me to be in London.

WILLIAM BuRTON.

CLIFTON JUNCTION,

October, 1906.

Contents

I.—INTRODUCTORY é : . Z Z II.—WuHat THE VARIOUS PORCELAINS ARE MADE OF, . III.—THE SHAPING, GLAZING, AND FIRING OF PORCELAIN . IV.—THE COLOUR DECORATION OF PORCELAIN . - V.—OuUR KNOWLEDGE OF CHINESE PORCELAINS > : VI.—THE EARLIEST CHINESE PORCELAINS : - ‘ VII.—PORCELAINS OF THE MING Dynasty (1368-1643) 3 VITII.—PoRCELAINS OF THE CH’ING DyNasty (1644 TO DATE). THE REIGN OF K’ANG-HSI IX.—THE LETTERS OF PERE D’ENTRECOLLES ‘ X.—THE PORCELAINS OF THE PRESENT Dynasty (concluded) XI.—SoME SPECIAL CHINESE GLAZES : 2 ; XII.—JAPANESE PORCELAIN: INTRODUCTORY AND GENERAL XITI.—JAPANESE PORCELAIN: THE IMPORTANT CENTRES XIV.—A REVIEW OF THE HISTORY OF PORCELAIN IN EUROPE XV.—GERMAN PORCELAIN ; : ; XVI.—THE PORCELAINS OF HOLLAND, DENMARK, SWEDEN, RuSSIA, HUNGARY, AND SWITZERLAND XVII.—THE SOF?T-PASTE PORCELAINS OF FRANCE. XVIII.—THE Harb-PASTE PORCELAINS OF FRANCE XIX.—THE PORCELAINS OF Italy, SPAIN, PORTUGAL, AND BELGIUM . . = 3 > : r ; XX.—ENGLISH PORCELAIN: INTRODUCTORY : . : XXI.—THE ENGLISH PORCELAINS OF THE EIGHTEENTH CEN-

TURY : ; : A x ; = ; XXII.—THE ENGLISH PORCELAINS OF THE NINETEENTH CEN- TURY ; x : =

123 132

Chapter I Introductory

ALMOST everyone—certainly every collector—has an idea of what is meant by the word porceLaln, but all attempts to give a scientific definition of the term which shall admit neither of doubt nor of criticism have failed, for the simple reason that the name has always been applied in a very unsystematic fashion to substances of diverse kinds which have only certain surface-qualities in common. The word ‘* porcelain ’’ made its appearance in the flux of languages of the Latin tongue current in Europe during the Middle Ages from which the modern Italian, French and Spanish have grown. At first it seems to have been applied to rare pieces of artistry in carved shell or mother-of-pearl, doubtless because their white pearly surface recalled the sheen of the cowrie or Venus-shell, called by the Italians ‘‘Porcellana.’’* It seems practically certain that for some considerable time the word was used only to indicate such artistic objects as had this pearly sheen, for we find it applied in medizval inventories of the treasures of princes to widely different substances, while it was also used by the Italians to distinguish the whitest and brightest of their Majolica wares. When the Venetian traveller, Marco Polo, published his account of China in 1298, he gave the name to the material now known as Chinese porcelain, even though he used the same word to designate works carved in shell. By a process

* This name, itself equivalent to ‘‘little pig,’’ is said to have been given to this species of shell because of its shape. B a PORCELAIN.

of natural selection, as specimens of Chinese porcelain became more plentiful in Europe, the name was gradually restricted in its application, and ultimately was used in connection with pottery alone. As it happened, however, the European potters of the sixteenth and seventeenth centuries were absolutely ignorant of the nature of this porcelain of the Far East. Their wonder and admiration at its beauty drove them to attempt its manufacture, and many European substitutes were made, from the sixteenth century onwards, which had nothing in common with Chinese porcelain except certain qualities of colour and tone. Some writers, in their zeal for exact classification, would restrict the name now to those species of pottery, whether produced in Oriental or European kilns, which resemble Chinese porcelain not only in appearance, but in their materials and the methods of their manufacture. The true collector could never accept such a narrowing of his ideas as this limitation would imply, and he will continue to apply the name porcelain to many diverse kinds of pottery, so long as they possess certain distinctions of colour and texture that delight his eye and satisfy his touch.

Scientific precision of definition being, therefore, out of the question, let us proceed to examine into the qualities that any kind of pottery must possess before it may be considered to rank among the porcelains. If we could gather together examples of all the different kinds of pottery which the best authorities of every country would include in this great group, we should find that they possessed at least two or three features in common. First of all we should be struck with the general fineness of finish and the whiteness of both the body and the glaze.* Further, we should find that all the specimens were fairly hard, some of them, indeed, exceedingly hard in substance; but the most distinctive and precious quality of all is the translucence of the ware as seen on sharp edges, on thin lips or mouldings. Many species of modern earthenware or stoneware may approach or even surpass some kinds of porcelain in whiteness or hardness; while the thin, white salt-glaze ware

* This is, of course, excepting the class of coloured-glaze porcelains, more extensively made in the East than in Europe, of Staffordshire and the white-jasper ware of the great Wedgwood, both products of the eighteenth century, are quite translucent in thin pieces ; yet a trained eye would separate these from porcelain at once, because of a difference in the quality of the glazed surface. For the final beauty of any form of pottery depends on the way in which the light is reflected from its glaze, and it is this most precious possession of the porcelains which entitles them to be separated from the other species of pottery, even though it has been attained by the use of entirely different materials, and by widely diverse methods of fabrication.

We must first describe the various ways in which the porcelains have been made, and then we shall be in a position to understand why, as a class, they possess a texture and surface so much more subtle and beautiful than are to be found in the other kinds of pottery. The species of porcelain produced in our own times are many and varied, but they all originated in attempts to reproduce the porcelain of China; and though the Chinese were not the first people who made pottery which would nowadays be classed as porcelain, it is established beyond contradiction that it was their discovery of the possibility of making a translucent pottery from mixtures of natural clays and powdered rocks that formed the starting point of all the modern porcelains whether in Europe or in Asia. The method slowly elaborated by the Chinese, and only brought to perfection by them in the seventeenth or eighteenth centuries, may be briefly outlined. The potter prepares mixtures of various natural clays and rocks, all of which are complex silicates. For his clays he uses the purest and whitest procurable, to which he has given the name of kao-lin.* Along with this clay certain crystallised rocks, reduced to the finest state of subdivision and containing felspar and white mica, are used, and the mixture may need completing by the addition of pure silica in the form of ground white sand or of

* The Chinese name, kao-lin, literally means “ high-ridge,” and so applies only to the place from which the clay best suited for porcelain came from, The English name, China-clay, i.e, “the clay for making

China-ware,’’ is equal testimony to the source of the first porcelains known to us.

pulverised quartz. These ingredients must be compounded in such proportions that the resulting mass will possess sufficient plasticity to work as a potter’s clay, i.e. that it can be moulded, or ‘‘ thrown ’’ on the wheel ; and it must also be so refractory that the vessels shaped from it shall be capable of enduring a very high temperature of firing without serious de-formation. At the high temperature to which the ware is exposed during this firing, a gradual chemical interchange takes place between the various silicates composing the mixture. The fusible silicates, such as the felspar and mica, begin to melt and attack the free silica and the kao-lin, and when the changes are complete we get a dense, hard, white porcelain, quite translucent if sufficiently thin, and so vitrified as to elicit a ringing musical note if sharply struck. However intensely fired the body may be, it never becomes transparent or clear like a piece of glass, for the glassy silicates that result from the fusion are penetrated through and through with opaque needles or rodlike crystallites, probably consisting of a silicate of alumina analogous to the mineral Sillemanite. Porcelain made in this way is generally spoken of as True or Natural porcelain; True, because the methods are those used by the Chinese, the originators of the method; and Natural, because all the substances employed are such only as Nature has prepared for our use in her ancient laboratory, the earth. Other names in current use are Kao-linic or Felspathic, from the fact that kao-lin and felspar are its principal ingredients; while the terms ‘‘hard’’ or ‘‘ hard-paste’’ porcelain are also used because of the intense hardness of the fired material.

There seems to be a general idea that there is only one kind of kao-linic porcelain, and that whether we are dealing with the ware of China, Japan, Meissen, Copenhagen, or Limoges, they are one and the same in composition and quality. It is difficult to imagine how such a view can ever have obtained credence, for every collector must have been struck with the different aspect of these varieties of porcelain. Contrast, for instance, the hard, almost harsh whiteness of a piece of French porcelain, made, say, between 1800 and 1870, with the luscious depth and softness of a piece of Chinese blue-and-white. No one with the slightest artistic perception could fail to feel, almost painfully, the difference in quality between the two products. This difference in quality is directly traceable to differences of composition among the various kinds of true or hard porcelain. This point will be dealt with more fully in the succeeding chapters, but it must be emphasised at the outset that there are many distinct varieties among the hard-paste porcelains alone.

When Chinese porcelain first startled the European nations nothing was known of its composition or the methods of manufacture. The earliest European porcelains, whether of Italy or of France, were made by mixing together a small proportion of white-firing clay with a large proportion of an artificial fusible silicate, such as frit or glass. When such mixtures are fashioned and fired the glass begins to soften and melt, enveloping and partly dissolving the clay, so that again a material is obtained in which a clear transparent base holds in suspension white and opaque particles, and such substances consequently exhibit something of the soft translucence that distinguishes the porcelains as a class. The porcelains thus made in imitation of the Chinese are generally distinguished as artificial or glassy porcelains, because of the use of artificial silicates, e.g. frit or glass, to replace the natural fusible silicates of the earlier true porcelains.

This artificial porcelain made from mixtures of clay and glass was, however, very difficult of management, for the mass was so deficient in plasticity that it was not easy to fashion articles from it; and though the temperature needed to melt the glass‘in the paste was much lower than that needed to melt the fusible silicates of true porcelain, the pieces were far more readily deformed by slight irregularities in the firing. Its manufacture was therefore always hazardous and uncertain ; attended with so much loss, in fact, that it could only be continued at the expense of some great prince or sovereign. It was, indeed, generally abandoned on account of these difficulties as soon as a knowledge of the Chinese materials became common, or when more manageable mixtures were found that would give comparable results. In France, where the artificial glassy porcelain reached its highest development, it was supplanted by hard porcelain as soon as materials resembling those used by the Chinese were discovered and worked. In England, where glassy porcelains were also largely made by the middle of the eighteenth century, the purely glassy mixtures were soon departed from, and other substances such as calcined ox-bones, steatite, &c., were added to the clay and frit to make mixtures that were more stable in the fire. After the discovery that minerals suitable for the manufacture of true porcelain occurred in Cornwall, the use of bone-ash still persisted, and a third type of porcelain was invented, known distinctively as English or bone-porcelain. In this case, a mixture of China-clay, China-stone (a natural mixture of felspar and quartz), and bone-ash is first prepared. This mixture possesses a fair amount of plasticity so that it can be readily shaped by the potter, and it attains the requisite degree of translucence at a temperature considerably lower than that needed for Chinese porcelain.

Though each of these types of porcelain admits of many subdivisions which are of great technical interest, it is sufficient for our present purposes to consider that all the porcelains belong to one of the following types :—

1. The natural felspathic porcelains. Such as ave made in China and Japan, as well as in Germany, France, Austria, Denmark, Sweden, &c.

2. The artificial glassy porcelains. Largely made in Italy, France, England and other European countries, in the eighteenth century.

3. The phosphatic or bone porcelains. Invented in England in the eighteenth century, and now made in England, America, France, Germany, Sweden, and elsewhere in Europe.

The members of the first group are distinguished by their whiteness, hardness, and complete vitrification, though of course different members of the group exhibit these qualities in different degree. The body is so hard that it cannot be scratched by a steel tool; it is impervious to staining fluids in the ordinary way, and if by chance it becomes chipped or shattered it exhibits a distinct conchoidal fracture, resembling that of a flint pebble.

The members of the second group are never quite so white in tint; they fritter away before a steel tool; they readily absorb staining fluids, and their fracture is distinctly granular, somewhat resembling that of loaf sugar, because as a matter of fact complete ‘‘ porcelainisation ’’ has not taken place.

The members of the third group are intermediate in every respect between those of the first two groups. Thus, they are generally whiter than the glassy porcelains and not so white as the felspathic porcelains; in hardness, in permeability and fracture they occupy a similar position, though they approach more nearly to the members of the first group than to those of the second. In fact, we may regard English bone-porcelain, so far as the body of the ware is concerned, as a true porcelain paste which has been rendered more fusible by the addition of a large proportion of calcium phosphate in the form of bone-ash.

Hitherto we have considered only the body or substance of the various porcelains, because that seems to be the simplest way of arriving at a clear understanding of a very complex subject. Let us now consider the question of the glaze, for this is the distinctive mark of the finest porcelains, and the source of their subtle beauty. In all porcelains of the first class, the glaze is composed of materials analogous to those used as the fusible ingredients of the paste, and as such materials are very refractory, they need to be fired at the same high temperature required to porcelainise the body. In China, the glaze, reduced to the finest possible state of subdivision, is generally applied to the pieces before they have been fired at all. In Europe and Japan the piece of shaped clay is fired at a moderate red-heat (from 600°-goo® C.) which expels all the water from it, and brings it to.a condition in which it is about as brittle and as porous’ as an ordinary clay tobacco-pipe, after which the glaze coating is applied. In either case the glaze and the body are then fired at a temperature varying from 1,350°- 1,500° C., so that, as we have said, the porcelainisation of the body and the fusion of the glaze go on side by side. It will be readily conceived that under such circumstances the melting glaze, containing fusible ingredients similar to those used in the body, will also attack and partly dissolve the outer layer of the body substance, and we may picture to ourselves a piece of glazed porcelain of the first class as consisting of many layers of different silicates, some of them of excessive thinness and none of them sharply defined, ranging from the outer skin of the glaze, which in perfect pieces is always the clearest, down to the body itself, which is a felted mass of minute crystalline rods imbedded in a more glassy substance. Only by forming some such mental picture, which is in harmony with the knowledge obtained by a microscopical examination of thin slices of the material, can we understand where the distinctive beauty of porcelain resides. When light falls upon a piece of true porcelain it penetrates these successive layers, which, so to speak, filter, soften and subdue it, so that the lowest depths shimmer and glisten with the light they reflect to the observer’s eye through the successive envelopes © of more translucent substance.

In the case of the other varieties of porcelain, the glaze and the glazing process are entirely different. The pieces of glassy-porcelain or of bone-porcelain having been fashioned and dried, are heated up to their vitrifying point, i.€. until they attain sufficient translucence, so that they are completely fired before the glaze is applied. When they are removed from the kiln after the first firing they are slightly porous, and they are then coated with a fine layer of powdered glaze, which is usually a glass rich in leadoxide, or in borax. The pieces are fired a second time at a temperature sufficient to melt this glaze coating; a temperature considerably less than that previously used to bake the body. Glazes made in this way are always thinner, more transparent and brilliant, more ‘‘ glassy,’’ in a word, than those in the first class, and from their nature and method of formation they lack the subtle depth and unctuous richness of the latter, because they affect the light less as it passes through them. A microscopical examination of thin slices of these lead-glazed porcelains, while it proves that there is a certain amount of analogy between all the porcelains, shows not less clearly the distinctions between them, and demonstrates the reasons for the difference of quality that the trained eye of a genuine collector perceives among the different members of the porcelain family. It goes without saying that, interesting as the differences of structure revealed by the microscope are, it is on the right training of his eye and a finely developed sense of touch that the collector must depend. Fine porcelains are too precious and beautiful to be wantonly sacrificed to the passion for analysis. Fortunately, too, there are many qualities, perfectly visible to the eye, that are generally sufficient to distinguish the different kinds of porcelain from one another. Many of these have been already mentioned (see pp. 6 and 7), and careful training by the examination and handling of typical specimens, using these indications as a guide, is the only way to prevent deception, either at the hands of ignorant or unscrupulous dealers, or, what is perhaps even more common, the self-deception that attends on imperfect knowledge.

Chapter II. What The Various Porcelains Are Made Of

THE porcelain collector may consider that he is not concerned with technical matters, but sufficient has already been said in the introductory chapter to show that the composition and nature of the different porcelains determine the qualities which enable us to distinguish between them, and on which every collector must found his judgment of the pieces he is anxious to acquire.

It seems to me, therefore, that it would be advisable to give here a preliminary sketch of the methods of porcelain-making, pointing out clearly those distinctions of material or method which have an active influence on the artistic qualities of the product. |

Such a course will doubtless save some confusion and needless repetition, and those who are already acquainted with the details of porcelain manufacture can easily skim or omit the technical chapters before proceeding to the chapters which will deal with the historical and artistic aspects of our subject.

It has too often been assumed—indeed, it has been explicitly stated by certain writers—that true porcelain, whether made in Europe or in the Far East, is practically identical in its nature and composition. Nothing could well be wider of the truth, and it is difficult to conceive how such an opinion could have been advanced when even chemical analysis, which can tell us so little with regard to artistic quality, had already shown that there must be wide divergencies of type between the ‘‘true’’ porcelains made in various countries.

The information supplied by the following analyses of different typical porcelains ought to convince anyone that

Io

WHAT PORCELAINS ARE MADE OF. Il such substances must possess very different chemical and physical properties :—

Crass I.—“ True” PorceLAINs.

As a general statement it may be sufficient to say that all ‘‘ true’’ porcelains are compounded practically from two ingredients, Kao-lin and Felspar, with a small proportion of silica in the form of quartz or sand, but the materials used by potters in their body-mixtures differ widely in different countries. Kao-lin, or China-clay, as it is quarried, washed, and prepared for the potter, is by no means a pure chemical substance such as a chemist would deal with in his laboratory. In fact, pure kao-lin, the definite hydrated silicate of alumina having the chemical composition given to it in text-books,* is practically non-existent. What the potter has to work with is some clay-substance approaching to this in composition but always containing variable percentages of other ingredients in addition, and the behaviour of any particular sample of kao-lin, or China-clay, may be very largely influenced by these other substances, especially when they happen to be substances that are fusible at lower temperatures than kao-lin itself. Pére d’Entrecolles, who sent to Europe the first definite information as to the materials used by the Chinese, noted particularly that their kao-lin ‘‘ was disseminated with corpuscles which are somewhat glittering,’? by which he evidently meant that the kao-lin contained particles of white mica as well as of

* Kao-lin is often assumed to be a definite substance for which such a formula as Al,O3;2Si0.2H,O might be written. This would correspond to 39°77 per cent. of alumina, 46°33 per cent. of silica, and 13:90 per cent. of water.

clay. Analyses of samples of the kao-lins used in China at the present day show that this mica may amount to 20 or 30 per cent. of the whole. Yet such mixtures of clay and mica, and the clay-substance used by a European potter from which all the mica has been carefully removed by washing and decantation, would both be described as kao-lin. Is it any wonder that the problems presented by the porcelains have proved so difficult to disentangle?

If this is true of the clay-substance used by the porcelain maker, the rocky minerals used to supply the fusible felspathic ingredients are even more variable. Within the last half-century the porcelain makers of Europe have had the advantage of being able to use the enormous masses of finely crystallised and remarkably pure felspar found in Sweden and Norway, and one may trace the fine and limpid whiteness of the modern porcelains of Copenhagen, Rorstrand, and other northern factories to this fact. Gener-— ally speaking, however, the porcelain maker does not use pure felspar, any more than he uses pure clay, in his mixtures. The general custom is to grind down to powder certain granitic rocks in which felspar is the predominant constituent. The Chinese potter, for instance, uses Pe-tun-tse,* the French or German potter pegmatite, and _the English potter China-stone, because all these are mineral substances, rich in felspar, which fuse down to a white, glassy mass at a high temperature. Similar as these substances, Pe-tun-tse, pegmatite, and China-stone, may be in general character, they are widely dissimilar in composition and fusibility. Beyond this, every practical potter knows that, with such mixed minerals, samples obtained from different parts of the same quarry exhibit surprising variations in fusibility. In ¢heory, therefore, all true porcelains consist of mixtures of chemically pure clay, felspar and quartz; while in practice, the potter of every country, even of every district, has certain natural clays and rocks to deal with—none of which is pure, many of

* This word, Pe-tun-tse, literally ‘‘ little-brick,”’ means nothing more than that the various rocks after being finely pulverised and washed are made into a paste with water, and sold to the porcelain maker in bricklike blocks.

which contain very diverse substances—and his task is to mix them together in such proportions as will give him a mass that he can fashion and fire into vessels of porcelain.

As a necessary corollary, while all the true porcelains have many qualities in common, there are wide divergencies of type to be met with even in this one group. If we consider, for instance, the porcelain produced at Sévres under the direction of Brongniart and his successors, we see the result of working under the guidance of scientific men who were concerned primarily with problems of manufacture and cared little for the esthetic charm of the substance manufactured. In the first place, all the clays and rocks were analysed, as correctly as was possible with the imperfect methods of silicate-analysis used, and the paste was compounded so as to approximate to a definite chemical composition. According to Brongniart,* the aim was to make a paste of the following composition :—