Calcium sulfate hemihydrate

Calcium sulfate hemihydrate (CAS 10034-76-1), also known as gypsum hemihydrate, is a partially dehydrated calcium sulfate produced by controlled calcination of natural gypsum.

Where is Calcium sulfate hemihydrate used?

• Construction: primary binder in plaster, drywall compounds and prefabricated gypsum boards
• Pharmaceuticals: tablet diluent and binder
• Pulp and paper: filler and surface treatment agent improving sheet formation, opacity and printability
• Dental and orthopedic casting: precision mold fabrication
• It reacts with water to form a rigid, dimensionally stable set mass.
• In dentistry, used as a bone regeneration graft material and graft binder/extender and as a barrier in guided tissue regeneration.
• When engineered for high purity, medical applications include use as a local drug delivery device.

Good to know: Alpha-hemihydrate offers higher density and compressive strength than the beta form.

Formulation notes

• As a tablet binder in pharmaceuticals, dosage is 2-5% binder.
• For dental casting, dosage is 100-200 g powder per 70-100 mL water.
• For orthopedic casts, dosage is 2-5 kg powder per 1-2 L water.
• In paper and cardboard as filler, dosage is 5-15% filler.

Typical specification

• Minimum purity of 98.00%.
• A 20% slurry in water has a pH between 6.5 and 8.5.
• Setting time is fast, 5-15 minutes.

Regulatory status

• It is a gypsum binder according to DIN EN 13279-1.

Storage, packaging and handling

• Calcium sulfate is hygroscopic, meaning it absorbs moisture.

Frequently asked questions about Calcium sulfate hemihydrate

What forms of calcium sulfate hemihydrate are available?

Calcium sulfate hemihydrate is available in Extrapure grade.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.