The technique of luster decorated pottery combines silver and copper oxides with sulfur and other materials, which are applied in liquefied form to the surface of a previously glazed and fired object. The ware is then refired in a muffled, or reducing, kiln, so that the oxygen is drawn out from the metal oxides, producing a dazzling metallic surface.
(source:The Los Angeles County Museum of Art)

 

Bowl, Iraq, ninth century
Earthenware, overglaze polychrome luster painted
2 3/4 x 91/2 in. (6.9 x 24 cm)
The Nasli M. Heeramaneck Collection, gift of Joan Palevsky