When buying gypsum from any supplier please ask the following questions when requesting delivered or ex works prices.
- Price $/tonne
- Do you have a recent analysis report (less than 6 months old) including
- Gypsum purity (%)
- Calcium and sulphur content (%)
- Sizing (top and mean size)
- Salt content %
- Moisture content %
Gypsum Quality Classification:
- Premium Grade Gypsum described as : Gypsum must contain a minimum of 89% purity, 16.5% sulphur (S) and a minimum of 21.0% Calcium (Ca).
- Grade 1 Gypsum described as : Gypsum must contain a minimum of 81% purity, 15.0% sulphur (S) and a minimum of 19.0% Calcium (Ca).
- Grade 2 Gypsum described as : Gypsum must contain a minimum of 67% purity, 12.5% sulphur (S) and a minimum of 15.5% Calcium (Ca).
- Grade 3 Gypsum described as : Gypsum must contain a minimum of 54% purity, 10.0% sulphur (S) and a minimum of 12.5% Calcium (Ca).
Purity of gypsum is calculated by dividing the Sulphur content % by 0.186 (i.e. gypsum with 100% has 18.6% Sulphur).
