Plaster cast is made up from dry muslin containing starch or dextrose and calcium sulfate.
Explanation:
It is applied to protect and is immobilize an injured bone or joint because it provides rigidity.
It is also used to help the bone and joint from reduce pain that is created during movement.
When plaster becomes wet,it reacts (Between water and calcium sulfate) and produces heat that eventually sets the plaster.It becomes hard when it dries.