File:Tempering standards used in blacksmithing.JPG

English: These "tempering standards" were cut from the same stock of carbon-steel flatbar. They measure 1/2" wide by 2" long. The one on the left has been normalized and sandblasted, to provide a diffuse surface, (for better photographing). The piece second-from-the-left is untempered quenched-steel, also sandblasted to remove any oxidation. The rest have also been quenched and sandblasted, but then tempered in an electric oven to their corresponding temperature, for around an hour each to thoroughly "soak" the metal in the heat. Tempering standards are often used by blacksmiths, to compare to work being tempered, ensuring that the work is tempered to the right temperature. (Tempering colors may appear different in different forms of lighting, or at different angles. For instance, to get good color-rendering, these needed to be photographed in the diffuse, continuous-spectrum light of a cloudy day.)