Aside from reducing the gypsum to a manageable size, crushing may include a process that dries the rock to remove any free moisture. The rock undergoes a fine grinding process prior to calcination, where the chemical composition of mined gypsum is transformed into a hemi-hydrate of calcium sulfate, making it suitable for commercial applications. Depending on the calcination method, the resulting plaster exhibits distinct properties and characteristics that affect its suitability for specific applications. G-P Gypsum Corporation conducts physical tests of our products in accordance with appropriate ASTM standard specifications and test methods established for various characteristics. Viscosity, strength and porosity are several of the important properties that can be accurately predicted from a slurry's consistency.
Low expansion is an important requisite for many applications.
Toward this end, we have established a strict program of quality assurance throughout our mining and production processes. All land plaster raw material must pass an incoming materials control test to ensure compliance with the G-P Gypsum Corporation standards. Precision measurement equipment and weight scales are used to grade and qualify material during the steps prior to processing. The ratio of water to gypsum is impacted by the calcination process. Separate and distinct calcination processes are used to produce the plaster desired.