Investment casting is an industrial process based on lost-wax casting. The castings themselves can be made from an original wax model by direct method or from a wax replica of a original model (indirect method). The properties of the special waxes for investment casting are critical to successful pattern production: contraction and cavitation; congealing and melting point; ash content; hardness and elasticity; viscosity; good surface finish; oxidation stability; reclaimability.