pottery and porcelain
Ceramic articles, especially vessels, made of clay (generally of kaolin) and hardened by firing. The simplest and oldest type of pottery, earthenware (nonvitreous), is soft, porous, and opaque, usually glazed and used for common tableware. Terra cotta is a primitive unglazed kind. Earthenware is fired to about 1,000°C. Stoneware, the first vitreous ware (of low porosity), was developed in China from the 5th to the 7th centuries AD. Fired to about 1,200°C, it is a hard, strong, nonabsorbent ware, opaque and cream to brown in color. From stoneware evolved porcelain during the Sung dynasty (960–1279). This is a hard, nonporous vitreous ware, white and translucent. Made from flint, kaolin (see kaolinite), and feldspar, it is fired to about 1,350°C.
In the manufacture of pottery the clay is made plastic by blending with water. The article is then shaped: traditionally, by hand, by building up layers of strips (coiled pottery), by "throwing" on the potter's wheel or by molding; industrially by high-pressure molding or by a rotating template. The clay is fired in a kiln, slowly at first, then at temperatures to oxidize and consolidate it. The glaze (if desired) is then applied by spraying or dipping, and the article refired. Glazes are mixtures of fusible minerals and pigments, similar to those used for enamel, powdered or mixed with water.
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