Page 28 - Curriculum Visions Dynamic Book

Firing clay
When clay is heated, its properties change dramatically, and the soft sticky material
is transformed into a hard brittle substance. This property is used for pottery and brick- making to make suitable shapes that can be set hard for use.
During intense heating, or firing, water that normally occurs between the sheets of the clay crystals is driven off, while quartz in the material melts. Thus the clay crystals become fused together by glassy silica.
China clay
China clay is a concentrated deposit of the mineral kaolinite. Kaolinite forms in large quantities when the hot fluids emanating from underground magma chambers intensely weather feldspar. Most china clay is white and can be used for porcelain and china. It is also used as a smooth coating on some paper.
 Air-dried pots being prepared for firing. The kiln can be seen in the background.
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