Enamelling

Enameling is gold and silversmiths technique executed by fusing powdered glass to a substrate by firing, usually between 750 and 850 °C (1380 and 1560 °F). The powder melts, flows, and then hardens to a smooth, durable vitreous coating on metal, and also glass or ceramics, although the use of the term "enamel" is often restricted to work on metal. The fired enameled ware is a fully laminated composite of glass and metal. The word enamel comes from the High German word smelzan (to smelt) via the Old French esmail.Used as a noun, "an enamel" is a usually small decorative object, coated with enamel coating. Enameling is an old and widely-adopted technology, for most of its history mainly used in jewellery and decorative art, but since the 19th century applied to many industrial uses and in everyday day consumer objects, especially cooking vessels. "Enamelled" and "enamelling" have a double "l" except in American English where "enameled" and "enameling" is preferred.

History
The ancient Egyptians applied enamels to pottery and stone objects, and sometimes jewellery, though the last less often than other ancient Middle Eastern cultures. The ancient Greeks, Celts, Russians, and Chinese also used enamel on metal objects.

Enamel was also sometimes used to decorate glass vessels during the Roman period, and there is evidence of this as early as the late Republican and early Imperial periods in the Levantine, Egypt, Britain and the Black Sea. Enamel powder could be produced in two ways; either through the powdering of colored glass, or the mixing of colorless glass powder with pigments such as a metallic oxide. Designs were either painted freehand or over the top of outline incisions, and the technique probably originated in metalworking. Once painted, enamelled glass vessels needed to be fired at a temperature high enough to melt the applied powder, but low enough that the fabric of the vessel itself was not melted. Production is thought to have come to a peak in the Claudian period and persisted for some three hundred years, though archaeological evidence for this technique is limited to some forty vessels or vessel fragments.

Enamel was at its most important in European art history in the Middle Ages, beginning with the Late Romans and then the Byzantines who began to use cloisonné enamel in imitation of cloisonné inlays of precious stones. This style was widely adopted by the "barbarian" peoples of Migration Period northern Europe. The Byzantines then began to use cloisonné more freely to create images, which was also copied in Western Europe. The champlevé technique was considerably easier, and very widely practiced in the Romanesque period. In Gothic art the finest work is in basse-taille and ronde-bosse techniques, but cheaper champlevé works continued to be produced in large numbers for a wider market.

From Byzantium or the Islamic world the cloisonné technique reached China in the 13-14th centuries; the first written reference is in a book of 1388, where it is called "Dashi ('Muslim') ware". No Chinese pieces clearly from the 14th century are known, the earliest datable pieces being from the reign of the Xuande Emperor (1425–35), which however show a full use of Chinese styles suggesting considerable experience in the technique. It remained very popular in China until the 19th century, and is still produced today. The most elaborate and highly-valued Chinese pieces are from the early Ming Dynasty, especially the reigns of the Xuande Emperor and Jingtai Emperor (1450–57), although 19th century or modern pieces are far more common. The Japanese also produced large quantities from the mid-19th century, of very high technical quality.

From more recent history, the bright, jewel-like colors have made enamel a favored choice for designers of jewelry and bibelots, such as the fantastic eggs of Peter Carl Fabergé, enameled copper boxes of Battersea enamellers, and artists such as George Stubbs and other painters of portrait miniatures. Enameling was a favorite technique of the Art Nouveau jewelers.

Enamel was first applied commercially to sheet iron and steel in Austria and Germany in about 1850. Industrialization increased as the purity of raw materials increased and costs decreased. The wet application process started with the discovery of the use of clay to suspend frit in water. Developments that followed during the twentieth century include enameling-grade steel, cleaned-only surface preparation, automation, and ongoing improvements in efficiency, performance, and quality.