An Encyclopaedia of Indian Archaeology v1.c16.s14.14

v1.c16.s14.14

Among the present day potters the practice of using magnetite to decorate pottery is not known. They use a suspension of finely ground red ochre in water. It is therefore possible that the PGW potter also, after wheel-throwing and sum-drying his pots, painted them with a suspension of ground red ochre in water. After painting he would bake the pots in an enclosed space under a reducing atmosphere on which red ochre turned into black magnetite on account of the following reaction taking place within the reducing atmosphere of the enclosed baking device: $3Fe₂O₃+CO-2Fe₃O₄+CO₂.Fe₃O₄$ is magnetic oxide of iron, i.e. magnetite. It is opaque, isometric and black with metallic lustre in reflected light.