  Biscuit.—The first stage of china after being fired. It is white and porous, and ready for decoration. Its surface resembles that of an ordinary clay pipe. China.—A term used to include all porcelains. Earthenware.—All ware that, in contradistinction to porcelain, is not translucent. Glaze.—The glassy substance applied to the surface of pottery and porcelain. Lead Glaze.—The porcelains of Bow, Chelsea, and other early factories contained as much as 40 per cent. of oxide of lead. Modern chinas contain less than half that, and some glazes are “leadless.” As to the terrible results of the use of this glaze on the health of the potters, see Report of Professors Thorpe and Oliver to Home Office on subject (C. 9207, 1899). Over-Glaze Decoration.—Decoration after the surface has received its transparent glaze. This decoration admits of a wider range of colours. On hard paste, such as Plymouth, it stands flat on the surface; on soft paste, such as Bow, it is partly incorporated. Under-Glaze Decoration.—Decoration applied to the unglazed surface when in biscuit state; the whole is then covered with transparent glaze and refired. Ironstone China.—A term invented by Mason, who took out a patent for his ware. It is not china, but is a heavy class of earthenware highly decorated. It was generally adopted by other Staffordshire makers. Moulds.—The models from which china is made. These are of plaster of Paris. Opaque.—Incapable of transmitting light. This distinguishes pottery from porcelain. Paste.—The body or material of which porcelain is made. Hard.—China which, on being broken, shows a sparkling surface like that of a flint stone, and is impervious to any staining by colour applied to it. Plymouth and Bristol and New Hall are the only true hard-paste porcelains of this country. Soft.—China which, on being broken, shows a porous surface capable of absorbing colour. Porcelain.—Commonly called china; is distinguished from pottery by being translucent. True Porcelain is made from a mixture of two minerals—petuntse, or “china stone,” and kaolin, or “china clay,” with nothing artificially added; e.g., Chinese, Dresden, Plymouth, and Bristol chinas. Glassy Porcelain, containing an artificial admixture of glass to give the paste translucency; e.g., Chelsea, Bow, Nantgarw, Pinxton. Bone-ash Porcelain, of which Spode’s china is an example. Pottery.—A term used to include all the earthenwares. Printing.—Formerly, in old chinas, all the coloured decorations were painted. Now, by use of various mechanical devices, women and girls are employed to transfer printed patterns on modern china. Transfer-printing.—A process used at Liverpool by Sadler and Green, and at Worcester, in which the design from an engraved copper plate was transferred to specially prepared paper and applied to the ware. Black and brown were the main colours used (see Illustrations, pp. 244-5 and facing p. 76). Translucent.—Transparent. All porcelains, when held up to a strong light, are translucent, in varying degree, according to thickness of paste. |
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