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CERAMICS, or KERAMICS (Gr. KEpapos, e...

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Originally appearing in Volume V05, Page 707 of the 1911 Encyclopedia Britannica.
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CERAMICS, or KERAMICS (Gr. KEpapos, earthenware), a general term for the study of the art of pottery. It is adopted for this purpose both in French (ceramique) and in German (Keramik), and thus has its convenience in English as representing an inter-national form of description for a study which owes much to the art experts of all nations, though " ceramic " and " ceramics " do not appear in English as technical terms till the middle of the 19th century. The word " pottery " (Fr. poterie) in its widest sense includes all objects fashioned from clay and then hardened by fire, though there is a growing tendency to restrict the word to the commoner articles of this great class and to apply the word "porcelain" to all the finer varieties. This tendency is to be deprecated, as it is founded on a misconception; the word " porcelain " should only be applied to certain well-marked varieties of pottery. The very existence of pottery is dependent on two important natural properties of that great and widespread group of rocky or earthy substances known as clays, viz. the property of plasticity (the power of being readily kneaded or moulded while moist), and the property of being converted when fired into one of the most indestructible of ordinary things. The clays form such an important group of mineral substances that the reader must refer to the article CLAY for an account of their occurrence, composition and properties. In this article we shall only deal with the various clays as they have affected the problems of the potter throughout the ages. The clays found on or close to the earth's surface are so varied in composition and properties that we may see in them one of the vital factors that has determined the nature of the pottery of different countries and different peoples. They vary in plasticity, and in the hardness, colour and texture of the fired product, through an astonishingly wide range. To-day the fine, plastic, white-burning clays of the south of England are carried all over Europe and America for the fabrication of modern wares, but that is a state of affairs which has only been attained in recent times. Even down to the 18th century, the potters of every country could only use on an extensive scale the clays of their own immediate district, and the influence of this controlling factor on the pottery of bygone centuries has never yet received the attention it deserves.' ' The archaeologist is frequently puzzled as to the place of origin. General Evolution of Pottery.—The primitive races of mankind, whether of remote ages or of to-day, took perforce such clay as they found on the surface of the ground, or by some river-bed, and with the rudimentary preparation of spreading it out on a stone slab if necessary and picking out any rocky fragments of appreciable size, then beating it with the hands, with stones or boards, or treading it with the feet to render it fairly uniform in consistency, proceeded to fashion it into such shapes as need or fancy dictated. Fired in an open fire, or in the most rudimentary form of potter's kiln, such pottery may be buff, drab, brown or red—and these from imperfect firing become smoked, grey or black. How many generations of men, of any race, handed on their painfully acquired bits of knowledge before this earliest stage was passed, we can never know; but here and there, where the circumstances were favourable or the race was quick of observation, we can trace in the work of prehistoric man in many countries a gradually advancing skill based on increased technical knowledge. For ages tools and methods remained of the simplest—the fingers for shaping or building up vessels, a piece of mat or basket-work for giving initial support to a more ambitious vase,—until some original genius of the tribe finds that by starting to build up his pot on the flattened side of a boulder he can turn his support so as to bring every part in succession under his hand, and lo! the potter's wheel is invented—not brought down from heaven by one of the gods to a favoured race, as the myths of all the older civilizations or barbarisms, Egyptian, Chaldean, Greek, Scythian, and Chinese have fabled, but born from the brain and hand of man struggling to fulfil his allotted task. Formerly every writer on the history of pottery seemed to imagine that the very rudest pottery must have been the invention of Egyptian, Chinese or some other distinct race from which the knowledge radiated to all the other races of the prehistoric world. No conception could be more erroneous. Since the middle of the 19th century research has established beyond doubt that wherever clay was found men became potters of a sort, just as they became hunters, carpenters, smiths, &c., by sheer force of need and slowly-gathered tradition. The not yet exploded view that Egypt or Assyria was the special cradle of this art, and that the pottery of the Greeks and Romans directly descended from such a parent stock, cannot survive in view of the incontestable evidence that pottery was made by the prehistoric peoples of what we now call Greece, Italy, Spain and other countries, long before they were aware that any other peoples lived on the earth than themselves. For centuries this simple hand-made pottery was hardened by drying in the sun, so that it would serve for the storage of dried grain, &c., but the increasing use of fire would soon bring out the amazing fact that a baked clay vessel became as hard as stone. Then, too, came the knowledge that even in one district all the clays did not fire to the same colour, and colour decoration arose, in a rude daubing or smearing of some clay or earth (a ruddle or bole perhaps), which was found to give a bright red or buff colour on vessels shaped in a duller-coloured clay—most precious of all were little deposits of white clay which kept their purity unsullied through the fire,—and by these primitive means the races of the dawn made their wares. On this substructure all the pottery of the last four thousand years has been built, .for behind all Egyptian, Greek or Chinese pottery we find the same primitive foundations. We now reach the beginnings of recorded history, and as the great nations of the past emerge from the shadows they each develop the potter's art in an individual way. The Egyptians evolve schemes of glowing colour—brilliant glazes fired on objects, shaped in sand held together with a little clay, or actually carved from rocks or stones; the Greeks produce their marvels of some example of ancient pottery—was it made in the district where it was found, or had it been imported from some other centre? When we possess a sufficient body of analytical data obtained by the use of one general chemical method, an analysis of a fragment will frequently enable such a question to be answered, where now all is doubt and speculation. Rut the analytical results published hitherto are often not worth the paper they are printed on for such a purpose, the older methods of silicate analysis being only approximate. of plastic form, and then, excited by their growing skill in metal work, turn the plastic clay into imitations of metal forms. These nations are overthrown, and the Romans spread some knowledge —only a tincture, it must be confessed--over all the lands they hold in fee; and from the Euphrates to the Atlantic, from Egypt to the Wall of Hadrian, they set alight potters' fires that have never since been extinguished. The Roman empire falls, and over Europe its pottery is forgotten along with its greater achievements; yet still pottery-making goes on in a very simple way, to be slowly revived and modified once more by the communities of monks, who, in later centuries, replace the Roman legions as the great civilizing influence in Europe. Meantime Egypt and the nearer East continued, in a debased form, the splendours of their glorious past, and glazed and painted pottery was still made by traditional methods. What part the Byzantine civilization and the Persians played during this obscure time, we are only just beginning to realize; but we now know that many interesting kinds of decorated pottery were made at Old Cairo, at Alexandria, at Damascus, in Syria, Anatolia and elsewhere (on which the later Moslem potters founded their glorious works), at a time when all over Europe crocks of simple red or drab clay, covered only with green and yellow lead-glazes, were the sole evidence of the potter's skill. What the Arab conquests destroyed, and what their breath quickened into life, we can only guess; but the fact is indisputable that with the Mahommedan con-quests there came a time when the potter's art of the Occident reached its highest expression, and when methods and knowledge hitherto confined to Egypt, Syria and Persia were spread from Spain and the south of France to India—even, it may be, into China. Meantime, in the farther East, the Chinese—the greatest race of potters the world has ever seen—were quietly gathering strength, until from their glazed, hard-fired pottery there emerged the marvellous, white translucent porcelain, one of the wonders of the medieval world. With the dawn of the 15th century of our era, the state of affairs was practically this:—In European countries proper we find rudely fashioned and decorated wares in which we can trace the slow development of a native craft from the superposition of Roman methods on the primitive work of the peoples. The vessels were mostly intended for use and not for show; were clumsily fashioned of any local clay, and if glazed at all then only with coarse lead-glazes, coloured yellow or green; in no case above the level of workmanship of the travelling brick- or tile-maker. The finest expression of this native style is to be found in the Gothic tile pavements of France, Germany and England, where all the colours are due to the clays and there is no approach to painting. In the Moslem countries—including the greater part of Spain and Sicily, Egypt and the nearer East, probably even to the very centre of Asia—pottery was being made either of whitish clay and sand, or of a light reddish clay coated with a white facing of fine clay or of tin-enamel, on which splendid decorative patterns in vivid pigments or brilliant iridescent lustres were painted. As early as the 12th century of our era this superior artistic pottery of the Moslem nations had already attracted the notice of Europeans as an article of luxury for the wealthy; and we may well believe the traditional accounts that Saracen potters were brought into Italy, France and Burgundy to introduce the practice of their art, while Italian potters certainly penetrated into the workshops of eastern Spain and elsewhere, and gathered new ideas. In Italy certainly, and in the south of France probably, efforts were continuously in progress to improve the native wares by coating the vessels with a white " slip " and drawing on them rude, painted patterns in green, yellow and purplish black. The increasing intercourse with Spain, in war and peace, also introduced the use of tin-enamel after the fashion of the famous Hispano-Moresque wares, and by the end of the 14th century a knowledge of tin-enamel was widespread in Italy and paved the way to the glorious painted majolica of the 15th and 16th centuries. From Italy and Spain, France and Holland, Germany, and finally, though much later, England learnt this art,and the tin-enamelled pottery of middle and northern Europe, so largely made during the 17th and 18th centuries, was the direct offshoot of this movement of the Italian Renaissance.' During the 15th and 16th centuries Chinese porcelain also began to find its way into Europe, and by the whiteness of its substance and its marvellous translucence excited the attention of the Italian majolists and alchemists. The first European imitation of this famous oriental porcelain of which we have indubitable record was made at Florence (1575–1585) by alchemists or potters working under the patronage, and, it is said, with the active collaboration of Francesco de' Medici. This Florentine porcelain was the first of those distinctively European wares, made in avowed imitation of the Chinese, which form a connecting link between pottery and glass, for they may be considered either as pottery rendered translucent or as glass rendered opaque by shaping and firing a mixture containing a large percentage of glass with a very little clay. After the cessation of the Florentine experiments we know of no European porcelain for nearly a century, though the importation of Chinese porcelain had largely increased owing to the activity of the various " India" companies. The next European porcelain, made like the Florentine of glass and clay, was that of Rouen (1673) and St Cloud (1696); and during the 18th century artificial glassy porcelain was made in France and England largely, and in other countries experimentally. German experimenters worked in another direction, and the first porcelain made in Europe from materials similar to the Chinese was produced at Meissen by Bottger (1710-1712). During the 18th century not only was there a very large trade in imported Chinese and Japanese porcelain; but there was a great development of porcelain manufacture in Europe; and in every country factories were established, generally under royal or princely patronage, for the manufacture of artificial porcelain like the French, or genuine porcelain like the German. The English made a departure in the introduction of a porcelain distinct from either, through adding calcined ox-bones to the other ingredients; and this English bone-porcelain—a well-marked species—is now largely made in America, France, Germany and Sweden as well as in England. By the end of the 18th century the risks and losses attendant on the manufacture of the French glassy porcelain had caused its abandonment, and a porcelain made from natural materials like the Chinese has since been generally made on the continent of Europe. The older tin-enamelled wares—derived from the Hispano-Moresque and the Italian majolica—so largely made in France, Holland, Germany and elsewhere during the 17th and 18th centuries, met with a fate analogous to that of the French porcelain. Tin-enamelled earthenware is always a brittle substance, soon damaged in regular use; so that, when, in the middle of the 18th century, the English potter first appeared as a serious competitor with a fine white earthenware of superior durability and precision of manufacture, the old painted faience gradually disappeared between the upper millstone of European porcelain and the nether millstone of English earthenware. The 19th century witnessed a great and steady growth in the output of porcelain and pottery of all kinds in Europe and the United States. Mechanical methods were largely called in to supplement or replace what had hitherto remained almost pure handicraft. The English methods of preparing and mixing the materials of the body and glaze, and the English device of replacing painted decoration by machine printing, to a large extent carried the day, with a great gain to the mechanical aspects of the ' It must always be borne in mind that, side by side with the production of artistic wares in all countries, the traditional craft of the village pot-maker continued, and has probably been less interfered with than is generally imagined, except in the British Isles. Any country market-place in Spain. Italy, Greece, France, Germany, or Holland is provided to-day with a simple peasant pottery little removed in its forms, its decorations, or its technical skill from the country work of the middle ages. In England the cheapness of machine-made pottery has largely destroyed such village industries. GENERAL] work and in many cases with an entire extinction of its artistic spirit. Even the hand-work that still remained was largely affected by the growing dominance of machinery; and the painting, gilding and decoration of pottery and porcelain, in the first half of the 19th century, became everywhere mechanical and hackneyed. During the latter half of the 19th century another influence was fortunately at work. Side by side with the increasing mechanica' perfection of the great bulk of modern pottery there grew up a school of innovators and experimentalists, who revived many of the older decorative methods that had fallen into oblivion and produced fresh and original work, in certain directions even beyond, the achievements of the past. The loth century opened with a wider outlook among the potters of Europe and America. In every country men were striving once again to bring back to their world-old craft something of artistic taste and skill. Technical Methods.— All primitive pottery, whether of ancient or of modern times, has been made by the simplest methods. The clay, dug from the earth's surface, was or is prepared by beating and kneading with the hands, feet or simple mallets of stone or wood; stones and hard particles were picked out; and the mass, well tempered with water, was used without any addition. From this clay, vessels were shaped by scooping out or cutting a solid lump or ball, by building up piece by piece and smoothing down one layer upon another or by squeezing cakes of clay on to some natural object or prepared mould or form. The potter's wheel, though very ancient, was a comparatively late invention, arrived at independently by many races of men. In its simplest form it was a heavy disk pivoted on a central point to be set going by the hand, as the workman squatted on the ground; and it may be seen to-day in India, Ceylon, China or Japan, in all its primitive simplicity (see fig. I). This form of potter's wheel was the only one known until about the Christian era, and then, in Egypt apparently, the improvement was introduced of lengthening the spindle which carries the throwing-wheel and mounting on it near the base a much larger disk which the potter could rotate with his foot, and so have both hands free for the manipulation of the clay (fig. 2). No further advance seems to have been made before the 17th century, when the wheel was spun by means of a cord working over a pulley; and though a steam-driven wheel was introduced in the middle of the 19th century, this form remains the best for the production of fine pottery. A prevalent misconception with regard to the potter's wheel needs correction. For anything beyond very simple shapes it is impossible to carry the work to completion on the wheel at one operation as is generally imagined. Ail that the potter can do while the clay is soft enough to " throw " on the wheel is to get a rough shape of even thickness. This operation completed, the piece is removed from the wheel and set aside to dry. When it is about leather-hard, it may be re-centred carefully on the wheel (the old practice), or placed in a horizontal lathe (since 16th century) and turned down to the exact shape and polished to an even, smooth surface. The Greek vase-makers were already adepts in what is often reckoned a modern, detestable practice. Many Greek vases have obviously been " thrown " in separate sections, and when these had contracted and hardened sufficiently they were luted together with slip, and the final vase-shape was smoothed and turned down on the wheel, and even polished to as fine a degree of mechanical finish as the modern potter ever attains. So too with the Chinese; many of their forms have been made in two or three portions, subsequently joined together and finished on the outside as one piece. Indeed; it is remarkable how the Greeks and Chinese had discovered for themselves many devices of this kind which are generally held up to opprobrium as the debased methods of a mechanical age. V. 23705 Always it should be borne in mind that the shaping of pottery by " pressing " cakes of clay into moulds is much older than the potter's wheel, and has always been the method of making shapes other than those in the round. The modern method of " casting " pottery by pouring slip, a fluid mixture of clay and water, into absorbent moulds seems to have originated in England about the middle of the 18th century; and this too is a genuine potter's method which does not merit the disapproval with which it has been generally regarded by writers on the potter's art. In all ages the work of the " thrower " or " presser " has been largely supplemented by the modeller, who alters the shape, and applies to it handles, spouts or modelled accessories at will. Firing.—The firing of pottery has become in modern times such a specialized branch of the manufacture that the student can only be referred here to the technological works mentioned in the bibliography at the end of this article. It is, however, necessary that we should briefly describe the earlier forms of potters' kilns used by the nations whose pottery counts among the treasures of the collector and the antiquary. Here again we now know that the primitive types of kiln used by the potters of ancient Egypt or Greece have not vanished from the earth; it is only in the civilized countries of the modern world that they have been replaced by improved and perfected devices. The potters of the North-West Provinces of India use to-day a kiln practically identical with that depicted in severest silhouette on the rock-tombs of Thebes; and the skilful Japanese remain content with a kiln very similar to the one shown in fig. 3. This Greek type of kiln was improved and enlarged by the Romans, and its use seems to have been introduced wherever pottery was made under their sway, for remains of Roman kilns have been found in many countries (see fig. 4). With the end of Roman dominance we have ample evidence that their technical methods fell into disuse, and the northern European potter of the period from the 6th to the 12th century had to build up his methods afresh, and improved kilns were invented. The general type of medieval potter's kiln is illustrated for us in the manuscript of an Italian potter of the 16th century, now in the library of the Victoria and Albert Museum 1 (fig. 5). Kilns of a different type, horizontal reverberatory kilns, were used for making the hard-fired pottery of 1 I tre libri dell' Arte del Vasajo, by Cipriano Piccolpasso of Castel Durante, A.D. 1548. II Europe (Rhenish stoneware, &c.), as well as for Chinese porcelain and the earliest German porcelains. With the organization of pottery as a factory industry in the 18th century, improved kilns were introduced, and the type of kiln now so largely used in civilized countries is practically a vertical reverberatory furnace of circular section, from 10 to 22 ft. in diameter and of similar height, capable, there-fore, of containing at one firing a quantity of pottery that would have formed the output of a medieval potter for a year. Every device that can be thought of for the better utilization of heat and its even distribution throughout the kiln or oven has been experimented with; and, though the results have been most successful from the point of view of the potter, even the most recent coal-fired ovens remain very wasteful types of apparatus, the amount of available heat being relatively small to the fuel consumption. Gas-fired kilns and ovens are now being used or experimented with in every country, and their perfection, which cannot be far distant, will improve the most vital of the potter's processes both in certainty and economy. Glazes.—We are never likely to known when glaze (i.e. a coating of fired glass) was first applied to pottery, though the present state of knowledge would incline us to the opinion that the earliest glazed objects we possess are those of ancient Egypt,' but the practice may have been originated independently wherever a knowledge of the elements of glass-making had spread, as all the early glazes were of the alkaline type, which must first be fused into a glass before they can be applied to pottery. Many primitive races seem to have burnished their pottery after it was fired, in order to get a glossy surface; and in other cases the surface was rendered shining and waterproof by coating it with waxy or resinous substances which were often coloured. It is possible that the black varnish of Greek vases was obtained by such a method, and though that point is not settled, we have many types of primitive pottery, both modern and ancient, which are coated in this way. Such a coating is only a substitute for glaze in the work of peoples who do not know or have not mastered the technical secrets of true glazes. We can only consider as glazes those definite superficial layers of molten material which have been fired on the clay substance. Glazes are as varied as the various kinds of pottery, and it must never be forgotten that each kind of pottery Is at its best with its appropriate glaze. The earliest known glazes (Egyptian and Assyrian) were silicates of soda and lime containing very little alumina and no lead. Such glazes are very uncertain in use, and can only be applied to pottery unusually rich in silica (i.e. deficient in clay). Consequently these alkaline glazes cannot be used on ordinary clay wares, and when they have been used successfully, the clay has always been coated with a surface layer of highly siliceous substance (e.g. the so-called Persian, Rhodian, Syrian and Egyptian pottery of the early middle ages). The fact that glazes containing lead-oxide would adhere to ordinary pottery when alkaline glazes would not was discovered at a very early period; for lead glazes were extensively used in Egypt and the nearer East in Ptolemaic times, and it is significant that, though the Romans made singularly little use of glazes of any kind, the pottery that succeeded theirs, either in western Europe or in the Byzantine empire, was generally covered with glazes rich in lead. Throughout Europe, and over the greater part of the world, leaded glazes have been continuously used and improved for all ordinary pottery, and it is only with certain special hard-fired types of ware that they have yet been successfully replaced. Chinese porcelain and all the European porcelains made by analogous methods are fired at so high a temperature that a glaze by felspar softened by lime and silica is found most suitable for them, and the hard-fired stonewares, rich in silica, are often glazed with a salt glaze, or a melted earth rich in oxide of iron. Every kind of potter's clay (the mixture of clay, sand, flint, &c., from which the potter shapes his wares) has its own type of glaze, and from the earliest time down to our own what the potter could produce in form or glaze or colour has been largely decided for him by the clay material at his command. With any good plastic play ' The earliest glazed objects found in Egyptian tombs (once dignified by the name of Egyptian porcelain) are hardly to be called pottery at all, though we have no other name for them. The material is largely sand held together by a little clay and glass.which cannot be fired at the highest temperature, lead glazes have always proved the most practicable. A similar clay, to which large quantities of sand are added, may be glazed by the vapours of common salt; and mixtures rich in felspar, like Chinese or European porcelain, can be glazed by melting felspathic materials upon them. Naturally those species of pottery which are the hardest fired are the most durable—the glazes of hard porcelain are more unchangeable than lead glazes, and these in their turn than alkaline glazes. The most important types of glaze are (I) alkaline glazes (e.g. Egyptian, Syrian, Persian, &c.), the oldest and most uncertain; (2) lead glazes, the most widespread in use and the best for all ordinary purposes; (3) felspathic glazes, the glazes of hard-fired porcelains, generally unsuited to any other material; (4) salt glaze, produced by vapours of common salt, the special glaze of stonewares. Many intermediate glazes have been devised to meet special needs, but these remain the only important groups. Fuller details on this important subject must be sought in the technical works. Colours.—The primitive potters of ancient and modern times have all striven to decorate their wares with colour. The simplest, and therefore the earliest, colour decoration was carried out in natural earths and clays. The clays are so varied in composition that they fire to every shade of colour from white to grey, cream, buff, red, brown, or even to a bronze which is almost black. One clay daubed or painted upon another formed the primitive palette of the potter, especially before the invention of glaze. When glaze was used these natural clays were changed in tint, and native earths, other than clays, containing iron, manganese and cobalt, were gradually discovered and used. It is also surprising to note that some of the very earliest glazes were coloured glasses containing copper or iron (the green, turquoise and yellow glazes of the ancient Egyptians and Assyrians). Marvellous work was wrought in these few materials, but the era of the finest pottery-colour dawns with the Persian, Syrian and Egyptian work that preceded the Crusades. By this time the art of glazing pottery with a clear soda-lime glaze had been thoroughly learnt. Vases, tiles, &c., shaped in good plastic clay, were covered with a white, highly siliceous coating fit to receive glazes of this type, and giving the best possible ground for the painted colours then known. With this rudimentary technique the potters of the countries south and east of the Mediterranean produced, between the 9th and 16th centuries of our era, a type of pottery that remains ideal from the point of view of colour: for, with nothing more than the greens given by oxide of copper and iron, the turquoise of pure copper, the deep yet vivid blue of cobalt, the beautiful uncertain purple of manganese, and in certain districts the rich red of Armenian bole, they achieved colour schemes that have never been surpassed in their brilliant yet harmonious richness. When the coating of white siliceous clay was replaced by an opaque tin-enamel as in Spain, Italy, France, Holland, &c., a necessary change in the colour schemes resulted. At first only the copper-greens and cobalt-blues could be used on such a ground; the fine manganese purple turned to brown or black and the rich iron-reds to filthy shades of yellow. We cannot wonder that the Spanish-Arab potters paid more attention to their lustre decoration, fot'that was the natural thing to do. How strong and fine a palette could be evolved for use on a tin-enamel ground was shown by the Italian majolists of the 15th and 16th centuries; and when the later developments of tin-enamelled pottery took place in France, Holland, Germany, &c., their colour schemes are only echoes of Italian majolica crossed with Chinese porcelain. Delft, Nevers, Moustiers and Rouen may each charm us with its individuality; Nuremberg and other south German towns may show us that they too had mastered the use of tin-enamel; yet our minds always go back to the colour schemes of Italian majolica and of the Persian and Syrian pottery that lie behind and beyond them. The colours already spoken of were either clay colours or what are known as "under glaze" colours, because they were painted on th.E pottery before the glaze was fired. The earliest glazes of the Egyptians appear not to have been white, but were coloured throughout their substance, and this use of coloured glazes as apart from painted colour was developed along with the painted decoration by the later Egyptian, Syrian and Persian potters. Green, yellow and brown glazes were almost the only artistic productions of the medieval European potters' kilns, and their use everywhere preceded the introduction of painted pottery. The most extensive application of coloured glazes was, however, that made by the Chinese, who developed this type of colour decoration before they used painted patterns in underglaze colour. The earliest Chinese porcelains, and the hard-fired stone-wares out of which their porcelain arose, were decorated in this way, and the beauty of many of the early Sung coloured glazes has never been surpassed. With the exceedingly refractory felspathic glazes of Chinese porcelain very few underglaze colours could be used; and the prevalence of blue and white among the early specimens of Chinese porcelains is due to the fact that cobalt was almost the only substance known to the potters of the Ming dynasty which would endure the high temperature needed to melt their glazes. Consequently the Chinese were driven to invent the method of painting in coloured fusible glasses on the already fired glaze. They adopted for this purpose the coloured enamels used on metal; hence the common term " enamel decoration," which is so generally applied to painting in those colours which are attached to the already fired glaze by refiring at a lower temperature. With the introduction of this many-coloured Chinese porcelain into Europe the same practice was eagerly followed by our European potters, and a new palette of colours and fresh styles of decoration soon arose amongst us. Painting in on-glaze colours, being executed on the fired glaze, resembles glass painting, and it generally offers a striking contrast both in technique and colour-quality to the painting executed in colours under the glaze. In the former the work can be highly finished and the most mechanical execution is possible, but the colours are neither so rich nor so brilliant as under-glaze colours, nor have they the same softness as is given by the slight spread of the under-glaze colour when the glaze is melted over it. It must be pointed out that the colour possibilities in any method of pottery decoration are largely dependent on the temperature at which the colour needs to be fired. The clay colours are naturally more limited in range than the under-glaze colours, and these in their turn than the on-glaze colours. When, about the middle of the 18th century, European pottery took on its modern form, of earthenware made after the English fashion, and porcelain like the French and German, the lead or felspathic glazes used brought about another revolution in the potter's palette. The growing ideal of mechanical perfection discounted the freedom of the earlier brushwork, and printed patterns, or painting that might almost have been printed, removed the mind still farther from the richness of painted faience or majolica. It is useless to look for the glorious colour of Persian faience, Italian majolica, or Chinese porcelain, in modern wares produced by manufacturing processes where mechanical perfection is demanded to a degree undreamt of before the 19th century. The finest modern pottery colour is only to be sought in the work of those enthusiasts and experimenters who are striving to produce work as rich and free as the best of past times. Metals.—The noble metals, such as gold, platinum and silver, have, since the early years of the 18th century, been largely used as adjuncts to pottery decoration, especially on the fine white earthen-wares and porcelains of the last two centuries. At first the gold was applied with a kind of japanner's size and was not fired to the glaze, but for the last 150 years or so the metals have generally been fired to the surface of the glaze like enamel colours, by mixing the metal with a small proportion of flux or fusible ground glass. There can scarcely be a doubt that the ancient lustres of Persia, Syria and Spain were believed to be a form of gilding, though their decorative effect was much more beautiful than gilding has ever been. The early Chinese and Japanese gilding appears, like the European, to have been " sized " or water-gilt, not fired ; and it seems probable that the use of." fired " gold was taught to the Oriental by the European in the 18th century. To-day " liquid " gold is exported to China and Japan from Europe for the use of the potter.
End of Article: CERAMICS, or KERAMICS (Gr. KEpapos, earthenware)
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