BLUE TEMPERED SPRING STEEL STRIPS

[See Tempered Spring Steel Strip.] ?BLUING -(1] Sheets-A method of coating sheets with a thin, even film of bluish-black oxide, obtained by exposure to an atmosphere of dry steam or air, at a temperature of about 1000 F, generally this is done during box- annealing. (2] Bluing of tempered spring steel strip; an oxide film blue in color produced by low temperature heating.