ART 198 - HISTORY OF WORLD CERAMICS

Another technical innovation of the Ming Dynasty potters was the development of overglaze enamels as a way of increasing the color palette available on porcelain. The very high temperatures necessary to vitrify porcelain (above 2300° F) unfortunately eliminates many colors by causing them to 'burn out' during the firing. An ingenious 'work around' that was employed was to use overglaze enamels. First the glazed porcelain object was fired to around 2300°F to harden the clay and melt the clear glaze. After the firing, the piece appeared white. Next, on top of the already fired clear glaze, very low temperature glazes were applied by brushing. These low fired glazes, also called overglaze enamels, melt at approximately 1300°F, fusing onto the previously fired glaze rather than into it. Overglaze enamels are a surface phenomenon. Their advantage is that the color palette is extended into the pinks, yellows, oranges, reds, and purples which are much more restricted in the high temperature range. The disadvantage of overglaze enamel is impermanence. Colors can be abraded and worn with age and especially, use. Their use is therefore most always decorative. This example, called a baluster vase is indicative of the kind of effect possible with overglazing. Potters became very inventive with the technique. The jet black color seen here was difficult to obtain, and it was found that the best blacks resulted from a two-step process. First a layer of overglaze containing impure Chinese cobalt was applied and then a second layer of a copper green enamel was painted over this. On firing, the two layers fired together to produce this intense jet black. The image painted within the red border is one of courting birds resting on a flowering branch, a theme borrowed and used by the Japanese, especially in Kakiemon ware. Overglazing was first used at Jingdezhen.

Ming Dynasty Baluster Vase, Porcelain and Overglaze Enamel China, 1450-1650 CE, 16.5"