China; Ming Guo; ca. 1911; based on original from Qing dynasty
This brilliant black glaze was much prized in the 18th c. and its method of making was referred to by the Jesuit priest d'Entrecolle when he visited Jingdezhen, the imperial porcelain kiln city. The glaze was got by a mixing of iron with manganese oxide which had a certain percentage of cobalt in it and was applied to the unfired ceramic body. To achieve depth and richness several layers of glaze were applied and each fired separately (above 1200°C). After a time, because of the complexity of the process the quality of the glaze deteriorated. It was less brilliant and the colour became brown-black as here.