Firing in the investment casting process is the step where the molds are prepared to accept the molten alloy that will become the finished parts. The molds are transferred to special ovens that heat to 1,800º F. This flash-firing treatment melts and removes the wax (this is where the term “lost wax” process comes from) and sprue material. It also hardens the ceramic molds so they can withstand the heat and forces of a wide range of molten metals. Once the molds have been fired and de-waxed, they are placed on a bed of sand, ready for the next step.