Investment casting is an industrial process based on lost-wax casting, one of the oldest known metal-forming techniques. Investment casting is so named because the process invests (surrounds) the pattern with refractory material to make a mould, and a molten substance is cast into the mold. Materials that can be cast include stainless steel alloys, brass, aluminium, carbon steel and glass. The cavity inside the refractory mould is an exact duplicate of the desired part. Due to the hardness of refractory materials used, investment casting can produce products with exceptional surface qualities, which can reduce the need for secondary machine processes.