Calcium sulfate

Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates. It is known in the E number series as E516, and the FAO knows it as a firming agent, a flour treatment agent, a sequestrant, and a leavening agent. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. It has many uses in industry. Calcium sulfate causes permanent hardness in water. The main use of calcium sulfate is to produce plaster of Paris and stucco. These applications exploit the fact that calcium sulfate which has been powdered and calcined forms a moldable paste upon hydration and hardens as crystalline calcium sulfate dihydrate. It is also convenient that calcium sulfate is poorly soluble in water and does not readily dissolve in contact with water after its solidification. The calcium sulfate hydrates are used as a coagulant in products such as tofu. It has been used in bone regeneration as a graft material and graft binder/extender and as a barrier in guided tissue regeneration. It is an unusually biocompatible material and is completely resorbed following implantation.