Biscuit porcelain is specially suitable for figure modelling, because the sharpness of the details remains unobscured by glaze. It has been largely employed in European porcelain factories for this purpose, but the Chinese seem to have been prejudiced against this exclusive use of the material. As a rule they reserve it for the fleshy parts of their figures, giving the draperies a coating of glaze or of enamel or both. A rare example of the use of biscuit is illustrated in the catalogue of the Walters Collection (O. C. A., Plate XXIX.), a white bottle with a dragon carved out of the glaze and left in biscuit.
The white wares so far described were made of the ordinary porcelain body and glaze, but there is another group of whites which is ranked with the so-called “soft pastes.” This is a creamy, opaque and often earthy-looking ware, the glaze of which is almost always crackled. It is in fact an imitation of the old Ting yao (q.v.), and its soft-looking surface and warm creamy tone are seen to perfection in small vases, snuff bottles, and ornamental wares. Indeed, the elegantly shaped and finely potted vessels of this soft, ivory crackle are among the gems of the period.
Crackle is a feature which is common to many of the monochromes, and incidental mention has frequently been made of it in the preceding pages. It is essentially a Chinese phenomenon, dating back to the Sung dynasty, and there are various accounts of the methods employed to produce it. We are speaking of the intentional crackle which is clearly defined and usually accentuated by some colouring matter rubbed into the cracks, as opposed to the accidental crazing which appears sooner or later on most of the glazes of the demi grand feu, and on many low-fired enamels. One crackling process used by the Sung potters has been described on p. [99], vol. i. Another method is mentioned in the K’ang Hsi Encyclopædia,[366] viz. to heat the unglazed ware as much as possible in the sun, then plunge it into pure water. By this means a crackle was produced on the ware after the firing.
But the normal process in the Ch’ing dynasty seems to have been to mix a certain ingredient with the glaze which produced a crackle when fired. There are constant references to this ingredient under the name of sui yu (crackle glaze) in the letters of Père d’Entrecolles in connection with various monochromes, and in the first letter,[367] the following definite account appears:—“It is to be observed that when no other glaze but that composed of white pebbles[368] is added to the porcelain, the ware turns out to be of a special kind known as tsoui ki (sui ch’i = crackled ware). It is marbled all over and split up in every direction into a infinite number of veins. At a distance it might be taken for broken porcelain, all the fragments of which have remained in place. It is like mosaic work. The colour produced by this glaze is a slightly ashen white.”
The effect of this ingredient of the glaze whatever its composition may have been is easily understood. All porcelain and pottery undergoes a considerable amount of contraction—from loss of moisture, etc.—in the kiln, and to obtain a perfectly even glaze it is necessary that the contraction of the glaze should be the same as that of the body. Clearly this ingredient caused the glaze to contract to a greater extent than the body, and so to split up into minute fissures. The Chinese were able to control to a great extent the size and nature of the crackle, as is shown by the appearance of alternate bands of large and small crackle on the same piece. The methods of colouring the crackle include rubbing red ochre, ink, and decoction of tea leaves into the cracks before the ware was quite cool. Another method is described by Bushell (O. C. A., p. 511) by which a white crackled ware was stained pink or crimson. The vessel was held in the fire in an iron cage until thoroughly heated, and then water mixed with gold-pink colouring matter was blown on to it. This, however, is a later process. Most of the monochrome glazes are occasionally crackled, but the most characteristic colours of the crackle glazes are the greyish white (the blanc un peu cendré of Père d’Entrecolles), and light buff, which were probably intended to recall the ash colour (hui sê) and the millet colour (mi sê) of the Sung Ko yao. Some of the light buff or “oatmeal” crackles of the early Ch’ing period are peculiarly refined and beautiful.
Though this has seemed a favourable opportunity for discussing crackle glazes it is not to be supposed that they were a speciality of the K’ang Hsi period. They are common to every age since the Sung dynasty, and probably they were never made in such abundance and with such care as in the Yung Chêng and early Ch’ien Lung periods.