This data sheet will provide hazards and safety information for certain traditional processes. These are all varieties of calcined gypsum, composed of calcium sulfate.
Plaster is mixed by sifting the powder into water.
Sometimes salt, potassium sulfate, or potassium alum is added to speed setting, or borax, diluted acetic acid, or burnt lime is added to retard setting of the plaster. Silica sand, vermiculite, sand, and coarse stone can be added to the plaster for textural effects. Wet or dry plaster is carved and modeled with special plaster carving chisels, knives, rasps, and scrapers and other tools. In situations where there is heavy inhalation of the dust, more severe respiratory problems can result. Borax is moderately toxic by ingestion, by inhalation, and by absorption through burns or other skin injuries.