Plaster of Paris or Stucco

Plaster of Paris or Stucco

Although plaster of Paris is widely used today its origins date back to more than 9000 years ago. Anatolia and Syria are regarded as being the birthplace of this beneficial substance. About 5000 years ago the Egyptians started making their own version of the plaster of Paris. They would heat gypsum in open-air fires and then crushed it to make it into a powder form. This would then be mixed with water in order to serve as the jointing material for their bricks and blocks.
The ancient Greeks have also experimented with gypsum to create something like plaster of Paris. They would use it for creating windows in their temples. The kind of plaster they used was in its transparent form. Similarly the Romans made use of plaster of Paris to cast statues. With the passage of time many different civilizations experimented with gypsum calcinations and much expertise was gained through trial and error. By the1700s the city of Paris had become the center for this kind of plaster.
At that time houses in Paris used to be made of wood. Plaster of Paris would be applied to these wooden walls in order to make them fire proof This was the law enforced by the King of France who had taken heed from the big London fire which destroyed the city in 1666. Since then continuous excavation of large gypsum deposits close to Paris has been taking place.
It is produced by incompletely dehydrating pure finely ground gypsum at a temperature somewhat lower than 185°C. Most plasters theoretically approach -CaSO4 + l/2H2O which contains about 6.2 per cent of water.