Tin-glazed_pottery Tin-glazed pottery is pottery covered in glaze containing tin oxide which is white, shiny and opaque. (See tin-glazing.) The pottery body is usually made of red or buff colored earthenware and the white glaze was often used to imitate Chinese porcelain. Tin-glazed pottery is usually decorated, the decoration applied to the unfired glaze surface by brush as metallic oxides, commonly cobalt oxide, copper oxide, iron oxide, manganese dioxide and antimony oxide.