Celadon production later spread to other regions in Asia, such as Japan, Korea and Thailand. Finer pieces are in porcelain, but both the colour and the glaze can be produced in earthenware. For many centuries, celadon wares were the most highly regarded by the Chinese Imperial court, before being replaced in fashion by painted wares, especially the new blue and white porcelain, under the Yuan dynasty. Celadon continued to be produced in China at a lower level, often with a conscious sense of reviving older styles. In Korea the celadons produced under the Goryeo Dynasty (918–1392) are regarded as the classic wares of Korean porcelain.
The celadon colour is classically produced by firing a glaze containing a little iron oxide at a high temperature in a reducing kiln. The materials must be refined, as other chemicals can alter the colour completely. Too little iron oxide causes a blue colour, too much olive and finally black; the right amount is between 0.75% and 2.5%.
This post is part of the Friday Greens meme.