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.

It reacts with water to form a rigid, dimensionally stable set mass, making it a core binder and setting agent across construction, industrial, and pharmaceutical manufacturing.

In building and construction, it is the primary binder in plaster, drywall compounds, and prefabricated gypsum boards, where controlled set time and surface hardness are critical.

Pharmaceutical manufacturers use it as a tablet diluent and binder, where its compressibility and inert profile support high-volume solid dosage production for various medications.

In pulp and paper operations, it functions as a filler and surface treatment agent to improve sheet formation, opacity, and printability for high-quality paper products.

Dental and orthopedic casting applications also rely on it for precision mold fabrication, where dimensional accuracy after setting is the primary requirement for the user.

The material is supplied as a fine white powder in both alpha and beta crystal forms, with alpha-hemihydrate offering higher density and compressive strength than the beta form.

Standard grades include USP, Ph. Eur., and food-grade (FCC) for regulated applications, alongside technical and construction grades for industrial use.