Plaster, Blanc Fixe and others

Selenite or gypsum (calcium sulfate dihydrate) is a commonly occurring natural mineral. When heated, water escapes and calcium sulfate hemihydrate is formed. This type of fired gypsum is found in alabaster, modelling or stucco plaster. When these powders are mixed with water, the plaster absorbs water again and hardens. Unfired gypsum is a component of Chalk from Bologna or occurs in pure form as alabaster, lenzine or selenite. It is used as a transparent filler in paints and primers.