Plaster is used as a building material similar to mortar or cement. After cementing of walls, POP is applied on it to smoothen the surface of walls. To stabilize the lime plaster during curing, small amounts of Plaster of Paris were incorporated into the mix. One of the skills used in movie and theatrical sets is that of "plasterer", and the material is often used to simulate the appearance of surfaces of wood, stone, or metal. Plaster expands while hardening, then contracts slightly just before hardening completely. This makes plaster excellent for use in moulds, and it is often used as an artistic material for casting. Plaster is often used in faux finishing to create textures for wall and furniture surfaces Plaster is widely used as a support for broken bones; a bandage impregnated with plaster is moistened and then wrapped around the damaged limb, setting into a close-fitting yet easily removed tube, known as an orthopedic cast. Plaster is also used within radiotherapy when making immobilization casts for patients. Plaster bandages are used when constructing an impression of the patients head and neck, and liquid plaster is used to fill the impression and produce a plaster bust. Perspex is then vacuum formed over this bust creating an immobilization shell. In dentistry, plaster is used for mounting casts or models of oral tissues. These diagnostic and working models are usually made from dental stone, a stronger, harder and denser derivative of plaster which is manufactured from gypsum under pressure. Plasters have been in use in passive fire protection, as fireproofing products, for many decades. Plaster of Paris has been allegedly used illegally by professional boxers to harden the hand wraps that boxers wear under their boxing gloves to protect their hands. Plaster of Paris has also been used to smuggle cocaine across many countries. The cocaine powder is mixed with the plaster mixture and sculpted.