Forged Cold Chisel

A cold chisel cuts cold metal, so its edge must be hard and its body tough. It is forged from octagonal tool steel: the head end is tapered, the blade drawn out at a yellow heat and finished with a flatter just above the hardening heat. Only the edge is hardened, by dipping it in water while the body stays hot, and the heat left in the body then tempers the edge; it is cooled when the edge shows blue tinged with red, about 570 °F (300 °C). The edge is ground to 60°.