Sèvres porcelain

“ The principal objection to a hard refractory glaze, such as that so long in use at Sèvres, arises from the difficulty of properly incorporating the enamel colours with its body. The restriction of the number of pigments that can be employed, both under and on the surface of the glaze, in consequence of the high temperature at which the latter melts, is another drawback. The dulness, the ‘painted on’ look of so much of the decoration on European hard paste porcelain, is in great measure a consequence of the employment of a glaze that is only softened at a high temperature. ”

“ There has been a reaction lately at Sèvres against this refractory ware, but the old formulas are still employed for the porcelain made for practical domestic use. When, however, brilliancy of effect and artistic decoration are aimed at, a completely new type both of paste and glaze has been in use since the year 1880, and concomitantly with the imitation of the Chinese monochrome wares, an attempt has been made to follow as closely as possible the pastes and glazes of the Chinese. ”

“ Soft porcelain, begun at St.-Cloud in 1695, continued there, and afterward at Chantilly; then at Vincennes, in 1745; still later at Sèvres, in 1756. The production of soft porcelain, or pâte tendre, continued at Sèvres, in company with that of the pâte dure, until 1804. 2. The hard porcelain, or pâte dure of the French; which was made after the discovery of the kaolin of St.-Yrieix, at Sèvres.
Marks used at St.-Cloud:
The mark of the Sun. ”

“ The palette of the European enameller is a more extensive one, and each large porcelain manufactory has its book of recipes. The composition of the enamels and the relation of the metallic oxides to the fluxes employed have been systematically studied in more than one laboratory. It is only at Sèvres, however, that the results obtained have been made public. It has been the pride of successive generations of chemists—of Brongniart, of Salvétat, of Ebelmen, not to mention living men—to devise fresh sources of colour for the decoration of porcelain. ”

“ In the case of the flambé or ‘transmutation’ glazes, the strange caprices of colour have their origin, in part at least, in the contrast of the red sub-oxide and the green silicate of copper. In the case of both these glazes everything depends on the regulation of the draught of the furnace in which they are fired. The French have lately been at great pains to master the difficulties attendant upon the development of the effects sought after, and some success has been attained not only on a porcelain ground as at Sèvres, but these glazes have also been applied to fayence at the Golfe St. ”

“ They are, indeed, foreign to the nature of porcelain, sacrificing the brilliant white ground which should be the basis of all decorative schemes.
When the colouring matter is subjacent to the glaze it must be of a nature to withstand the full heat of the subsequent firing; we are restricted therefore to colours ‘à grand feu.’ This practically confines us to cobalt and to certain combinations of iron and copper, as far as the ‘old palette’ is concerned. At Sèvres and elsewhere other metals have been made use of whose silicates withstand the extreme temperature of the kiln. ”

“ So again, starting from the flambé glaze of the Chinese, the modern potter is inclined to run riot with the numerous new materials at his command.
At Sèvres—I follow M. Garnier’s report—advantage has been taken of the new porcelain paste (that of the ‘milder’ Chinese type) to revive in the biscuit ware the reproductions of works of sculpture for which the factory was so renowned in the days of the pâte tendre. The pureness and softness of the material and the skill of the manipulation are noteworthy apart from the artistic merit of the work. ”

“ Porcelain was first made in England about the year 1745. The best period of the manufacture dates from 1750 to 1780, though some of the oldest factories have survived to the present day. English porcelain, or as it is better known as “China” ware, was made at Chelsea, Bow, Derby, Worcester, Plymouth, Bristol, and in Staffordshire. Some of the best porcelain from these places does not yield in beauty to the finest of Sèvres ware. ”

“ The eighteenth-century porcelain has a soft, velvety “feel,” the glaze not being so glassy as that of hard porcelain. A pen-knife can cause abrasion on soft-paste porcelain, while hard paste will nearly always repel even the pressure of a steel point drawn over it. With soft paste one can see through the glaze, as it were; with hard paste one cannot. The enamel of the soft paste of Sèvres presents a delicate, milky glaze, exquisitely distinctive. The{173} colors, too, show forth with velvety freshness. Bleu du roi—king’s blue—is the name given the cobalt blue of the decoration ”

“ It was not so much their lack of translucency or the softness of their paste that was at fault, but rather the fact that they made pretence to be something better than they really were ‘at heart.’ Compared to porcelain, they are as plated ware to real silver, and time and wear are apt only too soon to reveal the base nature of their body. Wherever the enamel is chipped off, the dirt lodges, and greasy matter finds its way into the porous paste, causing a wide spreading stain. ”

“ This is a practical, and, we may also add, a hygienic defect, that is now sometimes forgotten, the more so as nowadays our common table ware is free from this fault, and resembles fine porcelain in so far that the white, compact body is covered by nothing but the transparent glaze. In fact, as far as European experience is concerned, we may say, broadly, that the merits of porcelain compared with those of fayence are rather of a practical than of an artistic nature. ”

“ In describing the preparation of the paste much stress is laid upon the care taken to exclude all extraneous matter, especially that which may have been introduced into the kaolin or petuntse by way of adulteration. The slip for the glaze—for the latter the Chinese term ‘oil’ is retained—is said to be brought down from the mountains, where it is prepared, in a liquid form. The division of labour in the manufacture is carried so far that a piece of porcelain before completion may pass through the hands of as many as seventy workmen, to each of whom a separate task is assigned. ”

“ Marwood. "Should you leave any of these in a pottery clay they would cause you much trouble, for when the ware was fired the metals would melt and discolor your porcelain. Sometimes this happens with cheap chinas. I dare say you yourself have seen dishes that are specked with yellow, or have stains here and there. Sometimes you can also detect bluish particles. That means the cobalt has not been properly ground or sifted. In less expensive wares such defects are frequent. But there is no excuse for them when making fine quality porcelains." ”

“ There is here no necessity for concealing the natural white colour of the paste. In the case of many kinds of pottery, however, as in the ‘enamelled fayence’ of Delft and Italy, the glaze is rendered opaque by the addition of oxide of tin, so that the ill-favoured ground is concealed by a white shiny surface which may be made to resemble closely the natural surface of porcelain. ”

“ The latter was made to perfection in the K’ang Hsi period. Having no colours to distract the eye from surface blemishes, nothing short of absolute purity could satisfy the critic. In choice specimens the paste was fine, white and unctuous, the glaze clear, flawless, and of oily lustre, [360] the form was elegant and the potting true. Such pieces without blemish or flaw are the very flower of porcelain, whether they be of eggshell thinness (t’o t’ai) , half eggshell (pan t’o t’ai) , or of the substance of ordinary wares. ”

“ Beyond these, the colors used in decorating hard or natural porcelain are laid on the glaze, to which they adhere without incorporating themselves.
The great difficulties attending the manufacture of porcelain may now be estimated. The piece must pass through the kiln as many times as there are colors requiring different temperatures. Too much heat will blot out the delicate colors, too little will leave them dull. Those on artificial or soft porcelain sink into the glaze, and thus present a softness and creamy delicacy never seen on any other kind of ware. ”

“ The verdict of the T’ao lu, “extremely refined and elegant,” is fully justified by the porcelain itself no less than by its decoration.
Not the least deserving of this praise, though mainly made for export, is the important group discussed on page 209, viz. the saucer dishes, plates, tea and coffee wares, etc., of delicate white porcelain, painted, apparently at Canton, in the famille rose enamels. It is an “eggshell” porcelain, white, thin, and beautifully finished, and the dainty little conical or bell-shaped tea cups, though without handles, are the perfection of table ware. ”

“ It has been the aim of the writer to dwell more especially on the nature of the paste, on the glaze, and on the decoration of the various wares, and above all to accentuate any points that throw light upon the relations with one another—especially the historical relations—of the different centres where porcelain has been made. ”

“ In the case of both the paste and of the glaze, we have been dealing with a restricted group of elements, with alumina, lime, potash and soda; and apart from impurities unintentionally introduced, all the combinations of these bodies are colourless. We have now to consider the effect of introducing certain of the heavy metallic bases which combine with the excess of silica to form coloured silicates.{39}
The metals that give to Oriental porcelain its brilliant hues are few in number. ”

“ Several of these are in the British Museum, and they show a white compact body of close but granular fracture; the glazed face is a pure, solid-looking white, and the unglazed sides show a smooth, fine-grained ware which has assumed a pinkish red tinge in the firing. The coarser porcelains of the period would, no doubt, have similar characteristics in body and glaze. The finer wares are exemplified by the white bowls, of wonderful thinness and transparency, with decoration engraved in the body or traced in delicate white slip under the glaze and scarcely visible except as a transparency. ”

“ That precaution is equally necessary for use as for beauty, as the ware would be liable to be spoiled and corroded by a variety of substances, if not covered with a coating of this kind. In porcelain it consists of enamel, which is a fine white opake glass, formed of metallic oxyds, sand, salts, and such other materials as are susceptible of vitrification. The glazing of common earthen-ware is made chiefly of oxyd of lead, or sometimes merely of salt, which, when thinly spread over earthen vessels, will, at a certain heat, run into opake glass. ”

“ The same effect may be easily produced upon all terra-cottas of which the paste is more sensible to the changes of temperature than the exterior coating or glaze. In fayence this accident is of frequent occurrence; the red porous clay, being more expansive, draws away the enamel, which, being less elastic, is separated into fragments, and the greater the resistance the more they are multiplied. Now one of the qualities of porcelain is precisely to avoid this double action. ”

“ That first used was probably copied as closely as possible from the pastes of Saint-Cloud and Chantilly. It was a mixture of sand from Alum Bay and pipeclay from Dorsetshire, with an amount of glass, in the form of a frit, sufficient to ensure translucency. Before long the sand and clay were replaced in great measure by bone-ash, and we get the ‘natural soft paste’ especially characteristic of English eighteenth century porcelain. Finally, at the beginning of the next century Spode replaced the glassy frit by a mixture of kaolin and china-stone, retaining the bone-ash. ”

“ Then they dip a brush in the mixture and trace various designs on the porcelain, and when they are dry the glaze is applied. When the ware is fired, these designs emerge in a white which differs from that of the body. ”

“ In actual fact the Chinese ware to which the term “soft paste” is applied has an intensely hard body. The glaze, however, which is softer than that of the ordinary porcelain, contains a proportion of lead, and if not actually crackled from the first becomes so in use, the crackle lines being usually irregular and undecided. ”

“ If any substance soluble in water, such as borax or salts of the alkalis, enter into the composition of the glaze, these must be first partially fused in combination with the other materials to form a frit, a kind of imperfect glass. These frits, which enter so largely into the composition of soft-paste porcelain, are formed with the object of bringing the soluble constituents into an insoluble form before mixing with water to form the slip. There are indeed other practical reasons that render a preliminary partial fusion desirable. ”

“ Indeed, in all lands and at all times, iron, copper, cobalt, and manganese have been the principal sources of colour in the decoration not only of porcelain, but of most other kinds of pottery. As equal to these four metals in importance, but not strictly to be classed as colouring materials, we may place tin, the source of most opaque whites, and lead, which is the main fluxing element for our enamels. ”

“ This porcelain was not only very hard but was semi-translucent; by that I mean that if it was held to the light one could see the glow through it. It was not, of course, transparent like glass. These two qualities of hardness and translucence help us to distinguish porcelain from pottery. ”