Vitreous enamel

Vitreous enamel, also called porcelain enamel, is a material made by fusing powdered glass to a substrate by firing, usually between 750 and 850 °C (1,380 and 1,560 °F). The powder melts, flows, and then hardens to a smooth, durable vitreous coating. The word comes from the Latin vitreum, meaning 'glass'.View into a glass-lined chemical reactorTurb-mixer in a glass-lined chemical reactorSilver, silver gilt and painted enamel beaker, Burgundian Netherlands, c. 1425–1450, The CloistersThe Royal Gold Cup with basse-taille enamels; weight 1.935 kg, British Museum. Saint Agnes appears to her friends in a vision.A freehand enameled painting by Einar Hakonarson. In the forest, 1989St. Gregory the Great in painted Limoges enamel on a copper plaque, by Jacques I LaudinEarly 13th century Limoges chasse used to hold holy oils; most were reliquaries.Medallion of the Death of the Virgin, with basse-taille enamelThe Dunstable Swan Jewel, a livery badge in ronde bosse enamel, about 1400. British MuseumLouis George enamel watch dialIranian enamelLimoges? grisaille Stations of the Cross, Notre-Dame-des-Champs, Avranches Vitreous enamel, also called porcelain enamel, is a material made by fusing powdered glass to a substrate by firing, usually between 750 and 850 °C (1,380 and 1,560 °F). The powder melts, flows, and then hardens to a smooth, durable vitreous coating. The word comes from the Latin vitreum, meaning 'glass'. Enamel can be used on metal, glass, ceramics, stone, or any material that will withstand the fusing temperature. In technical terms fired enamelware is an integrated layered composite of glass and another material (or more glass).The term 'enamel' is most often restricted to work on metal, which is the subject of this article. Enamelled glass is also called 'painted', and overglaze decoration to pottery is often called enamelling. Enamelling is an old and widely adopted technology, for most of its history mainly used in jewelry and decorative art. Since the 19th century, enamels have also been applied to many consumer objects, such as some cooking vessels, steel sinks, enamel bathtubs, and stone countertops. It has also been used on some appliances, such as dishwashers, laundry machines, and refrigerators, and on marker boards and signage. The term 'enamel' has also sometimes been applied to industrial materials other than vitreous enamel, such as 'enamel' paint and the polymers coating 'enamelled' wire. The word enamel comes from the Old High German word smelzan (to smelt) via the Old French esmail, or from a Latin word smaltum, first found in a 9th-century life of Leo IV. Used as a noun, 'an enamel' is usually a small decorative object coated with enamel. 'Enamelled' and 'enamelling' are the preferred spellings in British English, while 'enameled' and 'enameling' are preferred in American English. The ancient Egyptians applied enamels to stone objects, pottery, and sometimes jewellery, although to the last less often than in contemporaneous cultures in the Near East. The ancient Greeks, Celts, Georgians, and Chinese also used enamel on metal objects.:1 Enamel was also 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 Levant, Egypt, Britain and around the Black Sea. Enamel powder could be produced in two ways, either by powdering coloured glass, or by mixing colourless 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 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.