Enamel was used in jewellery, applied to metal, from very early on - there are examples in the Tomb of Tutankhamun of c. 1325 BC.
Applied to pottery, it is first seen in Persian mina'i ware from the late 12th century, using a group of seven main colours.
[3] Some techniques use thin metal leaf, including mina'i ware as well as the more usual pigments, which are typically applied in a liquid or paste form, painted by brush, or using stencils or transfer printing.
From about 1770 to the mid 20th century it was the dominant decorative technique in expensive pottery, mostly porcelain, made in Europe, East Asia,[4] and (to a lesser extent) North America.
Today overglaze decoration is much less commonly used, other than in traditionalist wares, as the range of colours available in underglaze has greatly expanded.
[5][6] The kiln used for the second firing is usually called a muffle kiln in Europe; like other types of muffle furnaces the design isolates the objects from the flames producing the heat (with electricity this is not so important).