Hammering Scale into a Hot Metal Surface
As steel reaches a yellow heat, a tough scale of iron oxide forms on its surface. This can be collected as it falls away then deliberately thrown under the working faces of a power hammer as the metal is forged to shape. The tough nature of the scale, and the immense power of the hammer, cause it to be driven deep into the metal surface in a random and unpredictable way. The result is deep, rich and natural looking texture.