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Also called kiln wash. Bentonite An extremely plastic clay rich in montmorillonite which can be added in small quantities to clays or clay bodies to increase plasticity. Biscuit Pottery that has been fired but not yet glazed. Occasionally also bisque.( Bisque porcelain Unglazed porcelain as a final product, with a matt surface resembling marble.
Fire clay in a furnace. Fire clay is a range of refractory clays used in the manufacture of ceramics, especially fire brick. The United States Environmental Protection Agency defines fire clay very generally as a "mineral aggregate composed of hydrous silicates of aluminium (Al 2 O 3 ·2SiO 2 ·2H 2 O) with or without free silica." [1]
The defining mechanical property of clay is its plasticity when wet and its ability to harden when dried or fired. Clays show a broad range of water content within which they are highly plastic, from a minimum water content (called the plastic limit) where the clay is just moist enough to mould, to a maximum water content (called the liquid ...
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Clay tempered with sand, grit, crushed shell or crushed pottery were often used to make bonfire-fired ceramics because they provided an open-body texture that allowed water and volatile components of the clay to escape freely. The coarser particles in the clay also acted to restrain shrinkage during drying, and hence reduce the risk of cracking.
In the case of pottery, clay materials are shaped, dried and then fired in a kiln. The final characteristics are determined by the composition and preparation of the clay body and the temperature at which it is fired. After a first firing, glazes may be used and the ware is fired a second time to fuse the glaze into the body. A third firing at ...
The body of Longquan celadon, as seen in fragments under glaze, varies from "a heavy, compact grey stoneware to an almost white porcellaneous material", but where fired at the surface this turns to a typical terracotta reddish brown, seen at the unglazed foot of many pieces, and when relief decoration is left unglazed (see below and illustration).
A fire brick, firebrick, fireclay brick, or refractory brick is a block of ceramic material used in lining furnaces, kilns, fireboxes, and fireplaces. A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency .