 The red slip containing iron oxide was applied in a thick layer under the glaze.Even after the introduction of a range of different pigments, vessels were sometimes still produced with a restricted palette.The wares were glazed with a lead-alkaline-tin glaze, whose composition has been found from analysis to be lead oxide 25-30 percent, silica 45–55 percent, sodium oxide 8–14 percent and tin oxide 4–7 percent.