Lump of ancient Egyptian blue frit; found in Theban necropolis beginning of XVIIIth dynasty. Frit is a term referring to some of the ingredients of glass that are pre-heated until they are red-hot but not fused. These are then cooled and ground into powder, and added to the mixture of raw materials that are to be melted and fused together to make glass.As frit melts more readily than the original ingredients it facilitates fusion.