Wucai in the context of "Overglaze enamel"

Underglaze is a method of decorating pottery in which painted decoration is applied to the surface before it is covered with a transparent ceramic glaze and fired in a kiln. Because the glaze subsequently covers it, such decoration is completely durable, and it also allows the production of pottery with a surface that has a uniform sheen. Underglaze decoration uses pigments derived from oxides which fuse with the glaze when the piece is fired in a kiln. It is also a cheaper method, as only a single firing is needed, whereas overglaze decoration requires a second firing at a lower temperature.

Many historical styles, for example Persian mina'i ware, Japanese Imari ware, Chinese doucai and wucai, combine the two types of decoration. In such cases the first firing for the body, underglaze decoration and glaze is followed by the second firing after the overglaze enamels have been applied. However, because the main or glost firing is at a higher temperature than used in overglaze decoration, the range of colours available in underglaze is more limited, and was especially so for porcelain in historical times, as the firing temperature required for the porcelain body is especially high. Early porcelain was largely restricted to underglaze blue, and a range of browns and reds. Other colours turned black in a high-temperature firing.

Overglaze decoration, overglaze enamelling, or on-glaze decoration, is a method of decorating pottery, most often porcelain, where the coloured decoration is applied on top of the already fired and glazed surface, and then fixed in a second firing at a relatively low temperature, often in a muffle kiln. It is often described as producing "enamelled" decoration. The colours fuse onto the glaze, so the decoration becomes durable. This decorative firing is usually done at a lower temperature which allows for a more varied and vivid palette of colours, using pigments which will not colour correctly at the high temperature necessary to fire the porcelain body. Historically, a relatively narrow range of colours could be achieved with underglaze decoration, where the coloured pattern is applied before glazing, notably the cobalt blue of blue and white porcelain.

Many historical styles, for example mina'i ware, Imari ware, Chinese doucai, and wucai, combine the two types of decoration. In such cases the first firing for the body, underglaze decoration and glaze is followed by the second firing after the overglaze enamels have been applied.

Doucai (Chinese: 斗彩; Wade–Giles: tou-ts'ai) is a technique in painting Chinese porcelain, where 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 overglaze enamels of different colours and the piece fired again at a lower temperature of about 850°C to 900°C.

The style began in the 15th century under the Ming dynasty in the imperial factories at Jingdezhen, and its finest products come from a few years in the reign of the Chenghua Emperor, mostly small pieces like the famous Chicken cups. The style was discontinued after a few decades, as a suitable overglaze blue was developed, but later revived under the Qing dynasty. It is not to be confused with the wucai style, which was a related early technique for polychrome painting. Doucai can be translated as "contrasted colours", "fitted colours", "colours which fit together" or "dove-tailed colours".

China painting, or porcelain painting, is the decoration of glazed porcelain objects, such as plates, bowls, vases or statues. The body of the object may be hard-paste porcelain, developed in China in the 7th or 8th century, or soft-paste porcelain (often bone china), developed in 18th-century Europe. The broader term ceramic painting includes painted decoration on lead-glazed earthenware such as creamware or tin-glazed pottery such as maiolica or faience.

Typically the body is first fired in a kiln to convert it into a hard porous biscuit or bisque. Underglaze decoration may then be applied, followed by glaze, which is fired so it bonds to the body. The glazed porcelain may then be painted with overglaze decoration and fired again to bond the paint with the glaze. Most pieces use only one of underglaze or overglaze painting, the latter often being referred to as "enamelled". Decorations may be applied by brush or by stenciling, transfer printing and screen printing.