Calcium sulphate hemihydrate (CaSO4.1/2 H2O) is known as Plaster of Paris.
Plaster of Paris
Plaster of Paris is a white colour powder made up of gypsum.
- When water is mixed with it, the gypsum crystals are produced, leading to a hard mass.
- It has an exothermic setting process and may be catalysed by sodium chloride. It can be retarded by alum or borax.
- Plaster of Paris forms anhydrous calcium sulphate known as dead burnt Plaster of Paris.
There are three types of plaster
- Gypsum plaster
- Lime plaster
- Cement plaster
- Plaster of Paris is used as a building material by constructors and architects.
- It is an excellent moulding and casting agent for various purposes.
- Orthopaedics uses it to put casts around bone fractures.