Gypsum product having least expansion:
DENTAL STONE, HIGH STRENGTH (TYPE IV)
The principal requisites for a die material are strength, hardness, and minimal setting expansion. To obtain these properties, modified α-hemihydrate is used. The cube-shaped particles and the reduced surface area produce such properties without undue thickening of the mix. This material is also called die stone.
Impression plaster
Model plaster
Stone plaster
Die stone