Preparing a Pig Bed at Coltness Iron Works, early 1900s

These men are sieving the sand of the casting bed to remove impurities. Each time pig iron was cast in this sand sparks would fly from the molten metal and solidify into shards. These had to be removed before the sand moulds could be created for the next casting.

This photograph gives a good idea of the thickness of the walls surrounding the hearth at the base of each blast furnace. You can see that the stone walls have been reinforced with iron bars inside and out.