White ware

China clay or kmlin, which is predominantly kaolinite, is particularly valuable because it is essentially free from iron impurities (and therefore colourless). World production in 1991 was 24.7M1 (USA 39%, UK 13%, Colombia, Korea and USSR 7% each). In the USA over half of this vast tonnage is used for paper filling or paper coating and only 130000 tonnes was used for china, crockery, and earthenware, which is now usually made from ball clay, a particularly fine-grained, highly plastic material which is predominantly kaolinite together with clay-mica and quartz. Some 800000 tonnes of ball clay is used annually in the USA for white ware, table ware, wall and floor tiles, sanitary ware, and electrical porcelain. 

Other applications of ceramics require clay, either raw or purified, sand, and feldspar. Brick, porcelain, and white wares are made from these raw materials the main expenditure in making these products is in firing the mixtures of powders to a dense solid. Ordinary brick made from fire-clay requires a small amount of energy even refractory brick for high temperatures and chemical durability, made partly from purified oxides such as alumina or chrome ore,... 

Specification of hardness and phase composition of 22 white-ware products of different manufacturers... 

AMERICAN CERAMIC SOCIETY (ACerS). Founded 1899. It has 12,000 members. A professional society of scientists, engineers, and plant operators interested in glass, ceramics-iiielal systems, cements, refractories, nuclear ceramics, white wares, electronics, and structural clay products. It is located at 65 Ceramic Dr., Columbus, OH 43214. http //www.acers.org/... 

For many traditional ceramics such as structural elements (tiles, bricks, etc.), white-wares, (tableware, sanitaryware, etc.), and common refractories, the raw materials are naturally occurring minerals, and moderate levels of impurities are tolerated. More specialized technical ceramics such as electronic ceramics (substrates, electronic packages, capacitors, inductors, etc.) or high performance structural ceramics (silicon carbide, silicon nitride, etc.) demand low or controlled levels of impurities and make use of higher purity powders often made by more specialized techniques. 

There are, however, kaolins which possess a fair degree of plasticity, as the Georgia and Florida kaolins and some of the English china clays. These, as long as they maintain good whiteness, are highly valued in the manufacture of white ware and porcelain products. Frequently, however, increased plasticity is coincident with increased content of fluxes and consequent reduction in refractoriness. While marked plasticity in itself, of course, does not mean reduced refractoriness, it indicates geological conditions which tend to incorporate impurities in the clay. 

G. Y. Anders (Selas Corp., Dresher, Pa.), Proc. Fall Meeting, Material Equipment White Wares Diva., Amer. Ceram. Soc, 1970, p. 94. 

Since the production technology and the composition of raw materials were usually different in different ancient periods, data processing by SVM can be used for the differentiation of the periods of production of porcelain samples. Table 11.8 lists the glaze composition of white wares produced at Jingdezhen. These samples were produced in Song dynasty or Yuan dynasty. 

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