ADDITIVES - Pottery materials.
Additives are different pottery materials that have to be added to clay when in its natural state and while being manufactured, to make it pliable.
Grogs, sand and other materials can be added to clay to give strength, textures, improve colors and avoid shrinking. Combustible materials, rice, pasta, dried plants, etc. can be added to the clay so that during firing they will burn away, leaving a texture. Sand and grog of different colors and textures can be broken down and added. These do not burn away but give texture and strengthen the clay when fired.
Grogs can be made from different types of crushed red brick. If you sandpaper or use an electric saw for cutting and filing tiles, this will throw off very fine grog that can be used. Always make sure that what is to be added can be fired up to the same temperature as the clay being used, because like all clays, if over fired it will melt and bleed.
When certain clay colors are required, body stains can be purchased in powder form and mixed into the clay. It is always better to mix these with white clay as the color of the clay can affect the stains.
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