Overglaze enamels in the context of "Doucai"

Mina'i ware is a type of Persian pottery, or Islamic pottery, developed in Kashan in the decades leading up to the Mongol invasion of Persia and Mesopotamia in 1219, after which production ceased. It has been described as "probably the most luxurious of all types of ceramic ware produced in the eastern Islamic lands during the medieval period". The ceramic body of white-ish fritware or stonepaste is fully decorated with detailed paintings using several colours, usually including figures.

It is significant as the first pottery to use overglaze enamels, painted over the ceramic glaze fixed by a main glost firing; after painting the wares were given a second firing at a lower temperature. "Mina'i" (Persian: مینایی), a term only used for these wares much later, means "enamelled" in the Persian language. The technique is also known as haft-rang, "seven colours" in Persian. This term was used by the near-contemporary writer Abu al-Qasim Kasani, who had a pottery background. This technique much later became the standard method of decorating the best European and Chinese porcelain, though it is not clear that there was a connection between this and the earlier Persian use of the technique. As in other periods and regions when overglaze enamels were used, the purpose of the technique was to expand the range of colours available to painters beyond the very limited group that could withstand the temperature required for the main firing of the body and glaze, which in the case of these wares was about 950 °C.

Wucai (五彩, "Five colours", "Wuts'ai" in Wade-Giles) is a style of decorating white Chinese porcelain in a limited range of colours. It normally uses underglaze cobalt blue for the design outline and some parts of the images, and overglaze enamels in red, green, and yellow for the rest of the designs. Parts of the design, and some outlines of the rest, are painted in underglaze blue, and the piece is then glazed and fired. The rest of the design is then added in the overglaze enamels of different colours and the piece fired again at a lower temperature of about 850°C to 900°C.

It has its origins in the doucai technique. The usual distinction made with doucai, which also combines underglaze blue with overglaze enamels in other colours, is that in wucai only parts of the design include blue, and these cover wider areas, and are often rather freely painted. In doucai the whole design is outlined in the blue, even if parts are overlaid by the enamels and invisible in the finished product. Some parts may also be painted in the blue. However, this is not true of all pieces classified as doucai, especially from the 18th century onwards. Fragments of incomplete examples, only done in blue, have been excavated from waste tips at the kiln.