The English word, “plaster,” has a rather direct lineage from the Classical Greek emplassein meaning to “mold or form,” as well as the related term emplastron meaning to “daub, to salve.” For the latter term, you can think of plaster as a kind of “makeup” for walls and ceilings. The contemporary English pronunciation has effectively held these ancient words and original meanings more or less intact. The word plaster is still being used to describe a range of materials for casting, coating and beautifying our building.
Physically plaster begins as a wet, mineral slurry that has a chemical set, reacting with water or what is called a mechanical set, meaning that it simply dries out. The most important component of a plaster is its binder. As the name implies, it’s the component that binds or holds the plaster together. Think of it as a kind of mineral glue. Lime and gypsum are very common traditional binders. Plasters that exclusively use lime or gypsum are commonly referred to as lime plasters or gypsum plasters, respectively. There are other minerals that make can bind such as clay or natural cement and some of them can be used in combination.