OS05. Bloomery iron smelting slags and other residues

There are many variables in the smelting process, including the ores, the fuel and the clays used, the furnace construction, the method of blowing the furnace and the way in which the slag and bloom were removed. These result in a wide variety of slags and other residues. Although it is possible to define and describe some basic types of slag, in reality there is a more or less continuous transition from ore through slag to the finished iron. The materials to be described fall into four broad groups – the raw materials, the structural evidence, the waste products and the bloom.