Page 24 - Curriculum Visions Dynamic Book

(Left) Stoneware crockery is a cheaper form of tableware.
China clay (kaolin) is used almost exclusively because it is the only type of clay from which a
white, translucent, glassy ceramic can be made. Kaolin is made of very fine white platelets,
with no impurities, especially no iron to stain the clay.
The other benefit of kaolin is that it is a refractory clay, so that it can safely be fired at high temperatures without deforming. As kaolin fires in a kiln, it turns pure white.
Manufacturers of whiteware divide their products into three groups depending on how
much the firing has caused the clay to fuse together (vitrify).
Earthenware
Earthenware does not have a glassy finish. If it is to be used to hold liquids, it has to be glazed. It is
usually not pure white and is often tinted by iron staining. It is the cheapest form of white tableware.
To prevent frequent breaking, it has to be thicker and therefore heavier than other kinds of tableware because it is not fused. Earthenware is also glazed, coloured, and used
for wall tiles and extensively for sinks and bathroom objects.
(Right) A broken stoneware cup handle. You can see the thick handle typical of stoneware.
Stoneware
Stoneware is partly fused clay and has a much finer pore size than earthenware. It is used for tableware, for cooking pots, and for sanitary purposes in the form of drainpipes. Like earthenware, it has to be quite thick to protect it against breakage.
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