This steel is sent to a smith who breaks it down to small pieces and layers the steel according to carbon content, they smelt this in their forge and repeatedly fold the steel in order to homogenise it. The most important part of the forging is the tempering, when the sword is quench-hardened. In ancient times it was said that the soul of the sword was put into the katana at this point. The sword is sometimes given a rough polish by the smith and then sent to a professional polisher for polishing (usually to a mirror finish). After polishing, the sword to be fitted.