In sculpture, the most common method of processing metals is casting. The artist first creates his work in another material, such as clay or plaster. Then, in a special lab called a foundry, a mold of the work is constructed, and finally molten metal is poured into the mold at a very high temperature. The mold is removed once cool, producing a metal copy of the original work. Casting uses metal alloys, such as bronze, which is much stronger than plain copper. Other metal making methods include the forging and fusing of metal pieces in a variety of ways, such as welding. Today, new and modern materials are also used, like stainless steel metals. After the work is completed the artist can either opt to treat it with a protective material, like varnish or wax, leave the surface bare, or cover it with paint.