Peter's Pottery

What is clay?

Clay is a plastic, earthy material found in the ground. But often clay for pottery has been manufactured with the addition of a number of minerals, such as kaolin, silica and whiting. Firstly there is a common red clay called terracotta or earthenware. It is used for roof tiles, bricks, pipes and flower pots. It has been used successfully for ages for all types of storage and cooking pots, but is the weakest and most porous of the clays in use today. It is fired to a maximum temperature of about 1100 ^oC (2012 ^oF ). Secondly there is stoneware clay which is a grey or off-white color, and is denser, stronger and harder than earthenware. It is used for tableware. It is fired to a maximum temperature of about 1250 ^oC (2282 ^oF ). Thirdly there is porcelain. It is very fine and smooth and forms the most vitrified, or glassy body of all the clays. It is fired to a maximum temperature of about 1350 ^oC (2462^oF). It is mainly used for high quality tableware and ceramic art. There are various other clays, notably Raku clay, used for low temperature, fast firing, and also a midfire stoneware which matures under 1200 ^oC (2192 ^oF ). Lastly, but perhaps the most important in commercial use is Bone China clay. This is a paste-clay, which produces a very serviceable, white tableware.
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