A lead glaze is a glassy coating for pottery in which lead oxide is the main flux, allowing the glaze to melt at a relatively low kiln temperature. On earthenware it forms a smooth, glossy, slightly yellowish transparent surface that seals the porous body, and it can be coloured with metal oxides such as copper for green, iron for amber and brown and manganese for purple and black.
Lead glazes were used in the ancient world, by Roman potters and in Han dynasty and Tang dynasty China, where they produced the celebrated three-colour sancai wares. In medieval England, potters dusted powdered lead ore, or galena, onto jugs and pitchers before firing, giving the characteristic patchy green and orange glazes of medieval and post-medieval country pottery. Staffordshire potters of the eighteenth century refined lead glazes for slipware, above all, creamware, whose pale lead glaze helped it conquer the European table. Lead poisoning among pottery workers eventually led to strict regulation in Britain. Collectors should note that old lead-glazed wares are best kept for display rather than used with acidic foods or drinks, and that crazing, flaking and wear to the glaze affect both condition and value.
