Page "Clay" Paragraph 12

Clays exhibit plasticity when mixed with water in certain proportions.

When dry, clay becomes firm and when fired in a kiln, permanent physical and chemical changes occur.

These reactions, among other changes, cause the clay to be converted into a ceramic material.

Because of these properties, clay is used for making pottery items, both utilitarian and decorative.

Different types of clay, when used with different minerals and firing conditions, are used to produce earthenware, stoneware, and porcelain.

Prehistoric humans discovered the useful properties of clay.

Some of the earliest pottery shards recovered are from central Honshu, Japan.

They are associated with the Jomon culture and the deposits from which they were recovered have been radiocarbon dated to around 14000BC.

Depending on the content of the soil, clay can appear in various colors, from a dull gray to a deep orange-red.