Vitreous enamel

Since the 18th century, enamels have also been applied to many metal consumer objects, such as some cooking vessels, steel sinks, and cast-iron bathtubs.

This had been used as a technique to hold pieces of stone and gems tightly in place since the 3rd millennium BC, for example in Mesopotamia, and then Egypt.

[3] Although Egyptian pieces, including jewellery from the Tomb of Tutankhamun of c. 1325 BC, are frequently described as using "enamel", many scholars doubt the glass paste was sufficiently melted to be properly so described, and use terms such as "glass-paste".

The Staffordshire Moorlands Pan is a 2nd-century AD souvenir of Hadrian's Wall, made for the Roman military market, which has swirling enamel decoration in a Celtic style.

In Britain, probably through preserved Celtic craft skills, enamel survived until the hanging bowls of early Anglo-Saxon art.

[5][6] Mosan metalwork often included enamel plaques of the highest quality in reliquaries and other large works of goldsmithing.

Painted enamel remained in fashion for over a century, and in France developed into a sophisticated Renaissance and the Mannerist style, seen on objects such as large display dishes, ewers, inkwells and in small portraits.

A Russian school developed, which used the technique on other objects, as in the Renaissance, and for relatively cheap religious pieces such as crosses and small icons.

[8] In 1874, the government created the Kiriu kosho kaisha company to sponsor the creation of a wide range of decorative arts at international exhibitions.

[8] Gottfried Wagener was a German scientist brought in by the government to advise Japanese industry and improve production processes.

[8] Along with Tsukamoto Kaisuke, Wagener transformed the firing processes used by Japanese workshops, improving the quality of finishes and extending the variety of colours.

[12] Together with Hattori Tadasaburō he developed the moriage ("piling up") technique which places layers of enamel upon each other to create a three-dimensional effect.

[8] Ando Jubei introduced the shōtai-jippō (plique-à-jour) technique which burns away the metal substrate to leave translucent enamel, producing an effect resembling stained glass.

[9] With the greater subtlety these techniques allowed, Japanese enamels were regarded as unequalled in the world[16] and won many awards at national and international exhibitions.

The French traveller Jean Chardin, who toured Iran during the Safavid period, made a reference to an enamel work of Isfahan, which comprised a pattern of birds and animals on a floral background in light blue, green, yellow and red.

Copper began to be used for handicraft products after the Gold Control Act, was enforced in India which compelled the Meenakars to look for an alternative material.

Developments that followed during the 20th century include enamelling-grade steel, cleaned-only surface preparation, automation, and ongoing improvements in efficiency, performance, and quality.

[22] In Australia, abstract artist Bernard Hesling brought the style into prominence with his variously sized steel plates, starting in 1957.

[23] A resurgence in enamel-based art took place near the end of the 20th century in the Soviet Union, led by artists like Alexei Maximov and Leonid Efros.

Most modern industrial enamel is applied to steel in which the carbon content is controlled to prevent unwanted reactions at the firing temperatures.

Such enameled ferrous material had, and still has, many applications: early 20th century and some modern advertising signs, interior oven walls, cooking pots, housing and interior walls of major kitchen appliances, housing and drums of clothes washers and dryers, sinks and cast iron bathtubs, farm storage silos, and processing equipment such as chemical reactors and pharmaceutical process tanks.

Raw materials are smelted together between 2,100 and 2,650 °F (1,150 and 1,450 °C) into a liquid glass that is directed out of the furnace and thermal shocked with either water or steel rollers into frit.

[21] Colour in enamel is obtained by the addition of various minerals, often metal oxides cobalt, praseodymium, iron, or neodymium.

The only surface preparation required for modern ground coats is degreasing of the steel with a mildly alkaline solution.

[40] Enamel coatings applied to steel panels offer protection to the core material whether cladding road tunnels, underground stations, building superstructures or other applications.