A building material dating back over 9000 years, Plaster of Paris was used for creating monuments and casting human body parts. One of the earliest examples of plaster being used was by the ancient Egyptians who plastered the pyramid at Cheops. In 1666, after a massive fire engulfed the city of London, the King of France ordered the people of his country to plaster the walls and floors of their wooden homes to make them fire-proof.
Sculptors, decorative artisans, architects and engineers use Plaster of Paris to create test samples and molds for their designs. It was previously used by doctors to set broken bones.
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Calcination of gypsum which is partially dehydrated is what produces Plaster of Paris.
CaSO4 , ½ H2O
When plaster is mixed with warm water into a paste the consistency of pea soup, it takes about 20 minutes to set and up to 48 hours to completely cure.
How To Use
After mixing with warm water, Plaster of Paris can be poured into a mold or strips of gauze can be dipped into the mixture and wrapped around objects. As plaster cures, the temperature rises. It is not recommended to immerse body parts into plaster.
Plaster is an inexpensive material to experiment with and only requires mixing with water to activate.
Though plaster of Paris is good for some detail, there are better materials which are now available that give more accurate color-coded drying times and can produce greater detail. Plaster can also be brittle and have air bubbles which inhibit great detail and weaken the mold.