Plaster is a building material used for coating walls and
ceilings. Plaster starts as a dry powder similar to mortar or cement and like
those materials it is mixed with water to form a paste which liberates heat and
then hardens. Unlike mortar and cement, plaster remains quite soft after
setting, and can be easily manipulated with metal tools or even sandpaper.
These characteristics make plaster suitable for a finishing, rather than a
load-bearing material.
The term plaster can refer to gypsum plaster (also known as
plaster of Paris), lime plaster, or cement plaster.