Vase with a scene of farming and fishing

Underglaze Cobalt Blue Decoration

The technique of underglaze painting is a third-century innovation originating from Zhejiang province in southeastern China. To apply the underglaze design, the artist paints directly on the clay body before firing and glazing. This process produces a nontoxic decoration that does not fade.

The famed Chinese blue-and-white porcelain involves painting cobalt blue pigments as underglaze decoration over a white clay body and applying a clear glaze on top. The cobalt turns blue upon firing. The use of cobalt reflected the influence of the Islamic world, as cobalt ores were imported from Persia during the Tang dynasty (618–907).