A plaster casting is a stage in the creation of a piece of sculpture that is many times the last part of the work that is actually done by the sculptor. When the process of casting a piece of sculpture in plaster is finished, the work can be considered to be finished as well, even though the product that comes from the casting is quite fragile. The work can then be redone in bronze, lead or another metal; it can also be carved with a pointing machine into a piece of stone or marble.
If a piece of sculpture is not carved out of stone or other hard material, it is most often done in clay or wax. If it is done in clay it will eventually crumble into pieces unless it has been permanently kept damp or transformed into terra-cotta or plaster. When clay is baked, it becomes terra-cotta and results in a piece that is colored anywhere from brown-gray to red.