Blister steel is what you get when you carburize wrought iron, it comes out of the furnace with blisters on it, hence the name. Stack and weld, and you get shear. Stack and weld again, and you get double refined shear... once more for triple refined. All 4 grades were available in colonial America, used for different cultery needs, and often heavier tools would have a welded shear edge and a WI body. A farmer might get his axe "steeled" every season with a new blister or shear bit as the old one wore out. Razors would use triple-shear, as it had a more homogenized carbon content throughout, and fewer impurities, important in more precise tools.
|