Silversmithing has four distinct stages. The silversmith first saws or cuts a desired shape from sterling, fine silver sheet metal, or bar stock. The silver is filed, hammered, bent and worked at room temperature. When it becomes work-hardened, it must be heat-treated by annealing, making the metal soft again to prevent cracking. Silversmiths also use casting methods. After the forming and casting, pieces can be joined by soldering or riveting if necessary.