Identification

• Plaster is a mortar mixture that is used to coat surfaces such as walls or ceilings. When applied to the outside of a building, it is called stucco. It is made from a mixture of sand and either gypsum, lime or portland cement. Mixed with water, it creates a heavy paste material that hardens when it dries. Plaster provides a protective coating, insulating as well as adding protection from the elements and fire.
  
  

Features

• Plaster can be applied to masonry walls, but not directly to solid wood surfaces. Plaster bases are often used to help plaster adhere to the surface. Bases can be made from metal sheets or boards of gypsum, fiberboard or strips of wood. These are referred to as laths. Brick or stone can also be used as a plaster base. When applying the plaster to the base it is called plastering. The plaster is applied with a hand held tool called a trowel.
  
  

Significance

• After fires destroyed London in 1666, the King of France took steps to plaster the walls of Paris buildings, to help protect them from fire. In the 1700's Paris was known as the "capital of plaster," from which the term "Plaster of Paris" emerged. Gypsum, a sedimentary rock, one of the materials that can be used to make plaster, was mined near Paris.
  
  

History

• The history of plaster dates back some 9,000 years ago. Evidence of ancient plaster renders have been found in Syria and Anatolia. Plaster was used by the Egyptians when making the pyramids. Prepared gypsum was crushed and mixed with water and used as a sealer for the joints between the pyramid's blocks. The Egyptians also used plaster to make molds of human bodies. Romans used plaster to make copies of Greek statutes.
  
  

Benefits

• From early times plaster was used to coat walls, floors and ceilings. It was also used in decorative work. Plaster can be poured into molds, where it then hardens, and after the mold is removed the plaster takes on the shape of the mold. Crafters use plaster of Paris to create small statues and objects. Hair and fiber can be added to the plaster, which strengthens the material.