Plaster of Paris

The term plaster usually refers to plaster of Paris (also called gesso) — a mixture of powdered and heat-treated gypsum, which can be mixed with water (about 2 parts plaster to each part of water), hardening to a smooth solid which does not shrink or lose volume because it hardens before all the water can evaporate. Though heated in its manufacture, it needs no heat to mature the way ceramic clays do. A common building material as well as a versatile medium in sculpture, can be either the material cast in a mold or the material of a mold, a material to be modeled, or carved, or attached to something else. (

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