Pottery Types and Methods of Production
Pottery is the baked-clay wares of the entire ceramics field.
Types of Pottery
It usually falls into three main classes—porous-bodied pottery, stoneware, and porcelain. Raw clay is transformed into a porous pottery when it is heated to a temperature of about 500°C. This pottery, unlike sun-dried clay, retains a permanent shape and does not disintegrate in water. Stoneware is produced by raising the temperature, and porcelain is baked at still greater heat. In this process part of the clay becomes vitrified, or glassy, and the strength of the pottery is increased.
Methods of Production
Pottery is formed while clay is in its plastic form. Either a long piece of clay is coiled and then smoothed, or the clay is centered upon a potter’s wheel (used in Egypt before 4000 B.C.) that spins the clay while it is being shaped by the hand, or thrown. Decoration may be incised, and the piece is allowed to dry to a state of leather hardness before firing it in a kiln. The type of finish, depending on the kind or number of glazes, dictates the total number of firings. When slip and graffito are used, they are applied before the first firing. There are two types of fires—reducing and oxidizing. The former removes oxygen while the latter, a smokeless fire, adds it. Reduction and oxidation change the color of the fired clay and gave early potters their palette of red, buff, and black.