Plaster of Paris (Calcium Sulphate Hemihydrate)

Plaster of Paris is a quick-setting gypsum plaster made of fine white powder (calcium sulphate hemihydrate) that hardens when wet and left to dry. Plaster of Paris, known since antiquity, is so named due to its production from the plentiful gypsum found in Paris. When dry, plaster of Paris does not shrink or fracture, making it an excellent material for casting moulds. It is often used to create and hold decorative plasterwork on ceilings and cornices. It’s also used in medicine to produce plaster casts to keep broken bones immobilised while they recover, however many current orthopaedic casts are composed of fibreglass or thermoplastics.