Plaster

Plaster, mixture of water, sand, and lime used to coat walls and ceilings. Applied as a wet paste, it hardens as it dries. Plaster can be applied to various bases, such as brick, stone, or thin strips of wood or metal that are laid out parallel. It creates an airtight and durable finished surface. Several coats of plaster are usually necessary to build up the surface to the desired thickness. Materials such as hair or fiber can be added to plaster to make it stronger. Other kinds of materials can be added to make it fire resistant or sound absorbing.