Calcium sulfate dihydrate

Calcium sulfate dihydrate (CAS 10101-41-4), commonly known as gypsum, is the naturally occurring and synthetically produced hydrated form of calcium sulfate; approved as food additive E516.

Where is Calcium sulfate dihydrate used?

• Food: dough conditioner in bread manufacturing
• Food: coagulant in tofu processing, where controlled calcium ion release determines final texture
• Pharmaceuticals: tablet diluent and binder; low solubility supports controlled disintegration in direct compression formulations
• Agriculture: supplies calcium and sulfur to soil without significantly altering pH
• Construction: base material for plasterboard and wall plaster; cement retarder
• Oenology: used to acidify grape must in the production of liqueur wines.
• In must, added calcium sulfate reacts with tartrate ions to form insoluble calcium tartrate and release sulfate ions, lowering pH without increasing titratable acidity.
• Paper and pulp: used as a filler in coated paper.
• Paints: used as a white pigment or filler.

Formulation notes

• A common component of scale deposits in industrial heat exchangers because its solubility decreases with increasing temperature.

Typical specification

• Free water loss on drying 50 g at 40 °C to constant weight: less than 2%.
• Loss of free and bound water on drying at 200 °C for 4 hours: less than 23%.
• Lead content: less than 2 mg/kg.
• Oenological product: at least 90% calcium sulfate.

Regulatory status

• Occupational exposure limit (TLV) for the respirable fraction: 10 mg/m3 as a TWA.
• MAK value for the inhalable fraction: 4 mg/m³, pregnancy risk group C.
• The FAO of the UN recognizes calcium sulfate as a firming agent, flour treatment agent, sequestrant and leavening agent.

Storage, packaging and handling

• Must not be confused with the anhydrous form, which is very hygroscopic and solidifies on contact with must.
• Store at +5°C to +30°C.
• Store in a dry place, in airtight containers and away from volatile substances it could absorb.
• Commonly supplied in a 1 kg pack size.

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