Figure 37 Mugs, Staffordshire, ca. 1720. Salt-glazed stoneware. H. 5 3/4" and 6 5/8". These white dipped mugs have the addition of an iron-rich slip around the rim. Both mugs have areas of iron contamination, and the quart mug (right) has small areas of the white pipe-clay slip pulling away just below the rim interior.