Vitreous enamel, also called porcelain enamel, is a material made by fusing powdered

glass Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...

to a substrate by firing, usually between . The powder melts, flows, and then hardens to a smooth, durable vitreous coating. The word ''vitreous'' comes from the Latin , meaning "glassy". Enamel can be used on

metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...

ceramics A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porce ...

, 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. Essentially the same technique used with other bases is known by different terms: on glass as ''

enamelled glass Enamelled glass or painted glass is glass which has been decorated with vitreous enamel (powdered glass, usually mixed with a binder) and then fired to glass fusing, fuse the glasses. It can produce brilliant and long-lasting colours, and be tr ...

'', or "painted glass", and on pottery it is called '' overglaze decoration'', "overglaze enamels" or "enamelling". The craft is called "enamelling", the artists "enamellers" and the objects produced can be called "enamels". Enamelling is an old and widely adopted technology, for most of its history mainly used in

jewellery Jewellery (or jewelry in American English) consists of decorative items worn for personal adornment such as brooches, ring (jewellery), rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the ...

and

decorative art ] The decorative arts are arts or crafts whose aim is the design and manufacture of objects that are both Beauty, beautiful and functional. This includes most of the objects for the interiors of buildings, as well as interior design, but typical ...

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

cast-iron Cast iron is a class of iron–carbon alloys with a carbon content of more than 2% and silicon content around 1–3%. Its usefulness derives from its relatively low melting temperature. The alloying elements determine the form in which its car ...

bathtubs. It has also been used on some appliances, such as

dishwasher A dishwasher is a machine that is used to clean dishware, cookware, and cutlery automatically. Unlike dishwashing, manual dishwashing, which relies on physical scrubbing to remove soiling, the mechanical dishwasher cleans by spraying hot wat ...

s, laundry machines, and

refrigerator A refrigerator, commonly shortened to fridge, is a commercial and home appliance consisting of a thermal insulation, thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from its inside to ...

s, and on marker boards and

signage Signage is the design or use of signs and symbols to communicate a message. Signage also means signs ''collectively'' or being considered as a group. The term ''signage'' is documented to have been popularized in 1975 to 1980. Signs are any ki ...

. The term "enamel" has also sometimes been applied to industrial materials other than vitreous enamel, such as enamel paint and the polymers coating

enameled wire Magnet wire or enameled wire is a copper or aluminium wire coated with a very thin layer of insulation. It is used in the construction of transformers, inductors, motors, generators, speakers, headphones, hard disk head actuators, el ...

; these actually are very different in

materials science Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials sci ...

terms. The word ''enamel'' comes from the

Old High German Old High German (OHG; ) is the earliest stage of the German language, conventionally identified as the period from around 500/750 to 1050. Rather than representing a single supra-regional form of German, Old High German encompasses the numerous ...

word (to smelt) via the

Old French Old French (, , ; ) was the language spoken in most of the northern half of France approximately between the late 8th 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.

History

Ancient

The earliest enamel all used the cloisonné technique, placing the enamel within small cells with gold walls. 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 Mesopotamia is a historical region of West Asia situated within the Tigris–Euphrates river system, in the northern part of the Fertile Crescent. Today, Mesopotamia is known as present-day Iraq and forms the eastern geographic boundary of ...

, and then Egypt. Enamel seems likely to have developed as a cheaper method of achieving similar results.Osborne, 331 The earliest undisputed objects known to use enamel are a group of

Mycenae Mycenae ( ; ; or , ''Mykē̂nai'' or ''Mykḗnē'') is an archaeological site near Mykines, Greece, Mykines in Argolis, north-eastern Peloponnese, Greece. It is located about south-west of Athens; north of Argos, Peloponnese, Argos; and sou ...

an rings from

Cyprus Cyprus (), officially the Republic of Cyprus, is an island country in the eastern Mediterranean Sea. Situated in West Asia, its cultural identity and geopolitical orientation are overwhelmingly Southeast European. Cyprus is the List of isl ...

, dated to the 13th century BC. Although Egyptian pieces, including jewellery from the

Tomb of Tutankhamun The tomb of Tutankhamun (reigned ), a pharaoh of the Eighteenth Dynasty of Egypt, Eighteenth Dynasty of ancient Egypt, is located in the Valley of the Kings. The tomb, also known by its List of burials in the Valley of the Kings, tomb number KV ...

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". It seems possible that in Egyptian conditions the melting point of the glass and gold were too close to make enamel a viable technique. Nonetheless, there appear to be a few actual examples of enamel, perhaps from the Third Intermediate Period of Egypt (beginning 1070 BC) on. But it remained rare in both Egypt and Greece. The technique appears in the Koban culture of the northern and central

Caucasus The Caucasus () or Caucasia (), is a region spanning Eastern Europe and Western Asia. It is situated between the Black Sea and the Caspian Sea, comprising parts of Southern Russia, Georgia, Armenia, and Azerbaijan. The Caucasus Mountains, i ...

, and was perhaps carried by the

Sarmatians The Sarmatians (; ; Latin: ) were a large confederation of Ancient Iranian peoples, ancient Iranian Eurasian nomads, equestrian nomadic peoples who dominated the Pontic–Caspian steppe, Pontic steppe from about the 5th century BCE to the 4t ...

to the ancient Celts. Red enamel is used in 26 places on the Battersea Shield (c.350–50 BC), probably as an imitation of the red Mediterranean

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

, which is used on the Witham Shield (400–300 BC).

Pliny the Elder Gaius Plinius Secundus (AD 23/24 79), known in English as Pliny the Elder ( ), was a Roman Empire, Roman author, Natural history, naturalist, and naval and army commander of the early Roman Empire, and a friend of the Roman emperor, emperor Vesp ...

mentions the Celts' use of the technique on metal, which the Romans in his day hardly knew. The Staffordshire Moorlands Pan is a 2nd-century AD souvenir of

Hadrian's Wall Hadrian's Wall (, also known as the ''Roman Wall'', Picts' Wall, or ''Vallum Aelium'' in Latin) is a former defensive fortification of the Roman province of Roman Britain, Britannia, begun in AD 122 in the reign of the Emperor Hadrian. Ru ...

, 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 Anglo-Saxon art covers art produced within the Anglo-Saxons, Anglo-Saxon period of English history, beginning with the Migration period art, Migration period style that the Anglo-Saxons brought with them from the continent in the 5th century, ...

. A problem that adds to the uncertainty over early enamel is artefacts (typically excavated) that appear to have been prepared for enamel, but have now lost whatever filled the cloisons or backing to a champlevé piece. This occurs in several different regions, from ancient Egypt to Anglo-Saxon England. Once enamel becomes more common, as in medieval Europe after about 1000, the assumption that enamel was originally used becomes safer.

Medieval and Renaissance Europe

Waddesdon bequest British Museum DSCF9814 05

In European art history, enamel was at its most important in the

Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of global history. It began with the fall of the Western Roman Empire and ...

, beginning with the Late Romans and then the

Byzantine The Byzantine Empire, also known as the Eastern Roman Empire, was the continuation of the Roman Empire centred on Constantinople during late antiquity and the Middle Ages. Having survived the events that caused the fall of the Western Roman E ...

, who began to use

cloisonné Cloisonné () is an ancient technology, ancient technique for decorating metalwork objects with colored material held in place or separated by metal strips or wire, normally of gold. In recent centuries, vitreous enamel has been used, but inla ...

enamel in imitation of cloisonné inlays of precious stones. The Byzantine enamel style was widely adopted by the peoples of

Migration Period The Migration Period ( 300 to 600 AD), also known as the Barbarian Invasions, was a period in European history marked by large-scale migrations that saw the fall of the Western Roman Empire and subsequent settlement of its former territories ...

northern Europe. The Byzantines then began to use cloisonné more freely to create images; this was also copied in Western Europe. In

Kievan Rus Kievan Rus', also known as Kyivan Rus,. * was the first East Slavic state and later an amalgam of principalities in Eastern Europe from the late 9th to the mid-13th century.John Channon & Robert Hudson, ''Penguin Historical Atlas of Russ ...

a finift enamel technique was developed. Finift_01

Mosan metalwork often included enamel plaques of the highest quality in

reliquaries A reliquary (also referred to as a ''shrine'', ''chasse'', or ''phylactery'') is a container for relics. A portable reliquary, or the room in which one is stored, may also be called a ''feretory''. Relics may be the purported or actual physic ...

and other large works of goldsmithing.

Limoges enamel Limoges enamel has been produced at Limoges, in south-western France, over several centuries up to the present. There are two periods when it was of European importance. From the 12th century to 1370 there was a large industry producing metal o ...

was made in

Limoges Limoges ( , , ; , locally ) is a city and Communes of France, commune, and the prefecture of the Haute-Vienne Departments of France, department in west-central France. It was the administrative capital of the former Limousin region. Situated o ...

, France, the most famous centre of vitreous enamel production in Western Europe, though Spain also made a good deal. Limoges became famous for champlevé enamels from the 12th century onwards, producing on a large scale, and then (after a period of reduced production) from the 15th century retained its lead by switching to painted enamel on flat metal plaques. The champlevé technique was considerably easier and very widely practiced in the Romanesque period. In

Gothic art Gothic art was a style of medieval art that developed in Northern France out of Romanesque art in the 12th century, led by the concurrent development of Gothic architecture. It spread to all of Western Europe, and much of Northern Europe, Norther ...

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. Painted enamel remained in fashion for over a century, and in France developed into a sophisticated Renaissance and the

Mannerist Mannerism is a style in European art that emerged in the later years of the Italian High Renaissance around 1520, spreading by about 1530 and lasting until about the end of the 16th century in Italy, when the Baroque style largely replaced it ...

style, seen on objects such as large display dishes, ewers,

inkwell An inkwell is a small jar or container, often made of glass, porcelain, silver, brass, or pewter, used for holding ink in a place convenient for the person who is writing. The artist or writer dips the brush, quill, or dip pen into the inkwell ...

s and in small portraits. After it fell from fashion it continued as a medium for

portrait miniature A portrait miniature is a miniature portrait painting from Renaissance art, usually executed in gouache, Watercolor painting, watercolor, or Vitreous enamel, enamel. Portrait miniatures developed out of the techniques of the miniatures in illumin ...

s, spreading to England and other countries. This continued until the early 19th century. 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.

China

From either Byzantium or the Islamic world, the cloisonné technique reached China in the 13–14th centuries. The first written reference to cloisonné is in a book from 1388, where it is called "Dashi ('Muslim') ware".Sullivan, Michael, ''The arts of China'', 4th edn, p. 239, University of California Press, 1999, ,
Google books
/ref> No Chinese pieces that are clearly from the 14th century are known; the earliest datable pieces are from the reign of the Xuande Emperor (1425–1435), which, since they show a full use of Chinese styles, suggest considerable experience in the technique. Cloisonné remained very popular in China until the 19th century and is still produced today. The most elaborate and most highly valued Chinese pieces are from the early

Ming dynasty The Ming dynasty, officially the Great Ming, was an Dynasties of China, imperial dynasty of China that ruled from 1368 to 1644, following the collapse of the Mongol Empire, Mongol-led Yuan dynasty. The Ming was the last imperial dynasty of ...

, especially the reigns of the Xuande Emperor and

Jingtai Emperor The Jingtai Emperor (21 September 1428 – 14 March 1457), also known by his temple name as the Emperor Daizong of Ming and by his posthumous name as the Emperor Jing of Ming, personal name Zhu Qiyu, was the seventh List of emperors of the Ming ...

(1450–1457), although 19th century or modern pieces are far more common.

Japan

Japanese artists did not make three-dimensional enamelled objects until the 1830s but, once the technique took hold based on analysis of Chinese objects, it developed very rapidly, reaching a peak in the Meiji and Taishō eras (late 19th/early 20th century). Enamel had been used as decoration for metalwork since about 1600, and Japanese cloisonné was already exported to Europe before the start of the Meiji era in 1868. Cloisonné is known in Japan as , literally "seven treasures". This refers to richly coloured substances mentioned in Buddhist texts. The term was initially used for colourful objects imported from China. According to legend, in the 1830s Kaji Tsunekichi broke open a Chinese enamel object to examine it, then trained many artists, starting off Japan's own enamel industry. Early Japanese enamels were cloudy and opaque, with relatively clumsy shapes. This changed rapidly from 1870 onwards. The Nagoya cloisonné company ( existed from 1871 to 1884, to sell the output of many small workshops and help them improve their work. In 1874, the government created the company to sponsor the creation of a wide range of decorative arts at international exhibitions. This was part of a programme to promote Japan as a modern, industrial nation. Gottfried Wagener was a German scientist brought in by the government to advise Japanese industry and improve production processes. Along with Namikawa Yasuyuki he developed a transparent black enamel which was used for backgrounds. Translucent enamels in various other colours followed during this period. Along with Tsukamoto Kaisuke, Wagener transformed the firing processes used by Japanese workshops, improving the quality of finishes and extending the variety of colours. Kawade Shibatarō introduced a variety of techniques, including (drip-glaze) which produces a rainbow-coloured glaze and ( repoussé) technique, in which the metal foundation is hammered outwards to create a

relief Relief is a sculpture, sculptural method in which the sculpted pieces remain attached to a solid background of the same material. The term ''wikt:relief, relief'' is from the Latin verb , to raise (). To create a sculpture in relief is to give ...

effect. Together with Hattori Tadasaburō he developed the ("piling up") technique which places layers of enamel upon each other to create a three-dimensional effect. Namikawa Sōsuke developed a pictorial style that imitated paintings. He is known for (minimised wires) and (wireless cloisonné): techniques developed with Wagener in which the wire are minimised or burned away completely with acid. This contrasts with the Chinese style which used thick metal . Ando Jubei introduced the () technique which burns away the metal substrate to leave translucent enamel, producing an effect resembling

stained glass Stained glass refers to coloured glass as a material or art and architectural works created from it. Although it is traditionally made in flat panels and used as windows, the creations of modern stained glass artists also include three-dimensio ...

. The Ando Cloisonné Company which he co-founded is one of the few makers from this era still active. Distinctively Japanese designs, in which flowers, birds and insects were used as themes, became popular. Designs also increasingly used areas of blank space. With the greater subtlety these techniques allowed, Japanese enamels were regarded as unequalled in the world and won many awards at national and international exhibitions.

India and Islamic world

Enamel was established in the

Mughal Empire The Mughal Empire was an Early modern period, early modern empire in South Asia. At its peak, the empire stretched from the outer fringes of the Indus River Basin in the west, northern Afghanistan in the northwest, and Kashmir in the north, to ...

by around 1600 for decorating gold and silver objects, and became a distinctive feature of Mughal jewellery. The Mughal court was known to employ ''mīnākār'' (enamelers). These craftsmen reached a peak of during the reign of

Shah Jahan Shah Jahan I, (Shahab-ud-Din Muhammad Khurram; 5 January 1592 – 22 January 1666), also called Shah Jahan the Magnificent, was the Emperor of Hindustan from 1628 until his deposition in 1658. As the fifth Mughal emperor, his reign marked the ...

in the mid-17th century. Transparent enamels were popular during this time. Both cloissoné and champlevé were produced in Mughal, with champlevé used for the finest pieces. Modern industrial production began in

Calcutta Kolkata, also known as Calcutta (List of renamed places in India#West Bengal, its official name until 2001), is the capital and largest city of the Indian States and union territories of India, state of West Bengal. It lies on the eastern ba ...

in 1921, with the Bengal Enamel Works Limited. Enamel was used in

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

for colouring and ornamenting the surface of metals by fusing over it brilliant colours that are decorated in an intricate design called Meenakari. The French traveller Jean Chardin, who toured Iran during the Safavid period, made a reference to an enamel work of

Isfahan Isfahan or Esfahan ( ) is a city in the Central District (Isfahan County), Central District of Isfahan County, Isfahan province, Iran. It is the capital of the province, the county, and the district. It is located south of Tehran. The city ...

, which comprised a pattern of birds and animals on a floral background in light blue, green, yellow and red. Gold has been used traditionally for Meenakari jewellery as it holds the enamel better, lasts longer and its lustre brings out the colours of the enamels.

Silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...

, a later introduction, is used for artifacts like boxes, bowls, spoons, and art pieces.

Copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

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. Initially, the work of Meenakari often went unnoticed as this art was traditionally used on the back of pieces of ''kundan'' or gem-studded jewellery, allowing pieces to be reversible.

Modern

More recently, the bright, jewel-like colours have made enamel popular with jewellery designers, including the

Art Nouveau Art Nouveau ( ; ; ), Jugendstil and Sezessionstil in German, is an international style of art, architecture, and applied art, especially the decorative arts. It was often inspired by natural forms such as the sinuous curves of plants and ...

jewellers, for designers of bibelots such as the eggs of Peter Carl Fabergé and the enameled copper boxes of the Battersea enamellers, and for artists such as

George Stubbs George Stubbs (25 August 1724 – 10 July 1806) was an English painter, best known for his paintings of horses. Self-trained, Stubbs learnt his skills independently from other great artists of the 18th century such as Joshua Reynolds and Thoma ...

and other painters of

s. 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 20th century include enamelling-grade steel, cleaned-only surface preparation, automation, and ongoing improvements in efficiency, performance, and quality. Between the World Wars,

Cleveland Cleveland is a city in the U.S. state of Ohio and the county seat of Cuyahoga County. Located along the southern shore of Lake Erie, it is situated across the Canada–U.S. maritime border and approximately west of the Ohio-Pennsylvania st ...

in the United States became a center for enamel art, led by Kenneth F. Bates; H. Edward Winter who had taught at the Cleveland School of Art wrote three books on the topic including ''Enamel Art on Metals''. In

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, abstract artist Bernard Hesling brought the style into prominence with his variously sized steel plates, starting in 1957. A resurgence in enamel-based art took place near the end of the 20th century in the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

, led by artists like Alexei Maximov and Leonid Efros.

Properties

Ground vitreous enamel powder in different colors

Vitreous enamel can be applied to most metals. Most modern industrial enamel is applied to steel in which the carbon content is controlled to prevent unwanted reactions at the firing temperatures. Enamel can also be applied to gold, silver, copper,

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

, stainless steel, and

cast iron Cast iron is a class of iron–carbon alloys with a carbon content of more than 2% and silicon content around 1–3%. Its usefulness derives from its relatively low melting temperature. The alloying elements determine the form in which its car ...

. Vitreous enamel has many useful properties: it is smooth, hard, chemically resistant, durable, scratch resistant (5–6 on the

Mohs scale The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the Ger ...

), has long-lasting colour fastness, is easy to clean, and cannot burn. Enamel is glass, not paint, so it does not fade under

ultraviolet light Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of th ...

. A disadvantage of enamel is a tendency to crack or shatter when the substrate is stressed or bent, but modern enamels are relatively chip- and impact-resistant because of good thickness control and coefficients of

thermal expansion Thermal expansion is the tendency of matter to increase in length, area, or volume, changing its size and density, in response to an increase in temperature (usually excluding phase transitions). Substances usually contract with decreasing temp ...

well-matched to the metal. The Buick automobile company was founded by

David Dunbar Buick David Dunbar Buick (September 17, 1854 – March 5, 1929) was a Scottish-born American inventor, widely known for founding the Buick Motor Company. He headed this company and its predecessor from 1899–1906, thereby helping to create one ...

with wealth earned by his development of improved enamelling processes, c. 1887, for sheet steel and cast iron. Such enameled ferrous material had, and still has, many applications: early 20th century and some modern

advertising Advertising is the practice and techniques employed to bring attention to a Product (business), product or Service (economics), service. Advertising aims to present a product or service in terms of utility, advantages, and qualities of int ...

signs, interior

oven upA double oven A ceramic oven An oven is a tool that is used to expose materials to a hot environment. Ovens contain a hollow chamber and provide a means of heating the chamber in a controlled way. In use since antiquity, they have been use ...

walls,

cooking pot Cookware and bakeware is food preparation equipment, such as cooking pots, pans, baking sheets etc. used in kitchens. Cookware is used on a Kitchen stove, stove or range cooktop, while bakeware is used in an oven. Some utensils are considere ...

s, housing and interior walls of major kitchen appliances, housing and drums of clothes washers and dryers, sinks and

bathtub A bathtub, also known simply as a bath or tub, is a container for holding water in which a person or another animal may Bathing, bathe. Most modern bathtubs are made of thermoformed Acrylic resin, acrylic, porcelain enamel, porcelain-enameled s ...

farm A farm (also called an agricultural holding) is an area of land that is devoted primarily to agricultural processes with the primary objective of producing food and other crops; it is the basic facility in food production. The name is used fo ...

storage silos, and processing equipment such as

chemical reactor A chemical reactor is an enclosed volume in which a chemical reaction takes place. In chemical engineering, it is generally understood to be a process vessel used to carry out a chemical reaction, which is one of the classic unit operations in che ...

s and pharmaceutical process tanks. Structures such as

filling station A filling station (also known as a gas station [] or petrol station []) is a facility that sells fuel and engine lubricants for motor vehicles. The most common fuels sold are gasoline (or petrol) and diesel fuel. Fuel dispensers are used to ...

bus station A bus station, bus depot, or bus interchange is a structure where city buses or intercity buses stop to pick up and drop off passengers. A bus station is larger than a bus stop, which is usually simply a place on the roadside, where buses can st ...

s and Lustron Houses had walls, ceilings and structural elements made of enamelled steel. One of the most widespread modern uses of enamel is in the production of quality chalk-boards and marker-boards (typically called 'blackboards' or 'whiteboards') where the resistance of enamel to wear and chemicals ensures that 'ghosting', or unerasable marks, do not occur, as happens with polymer boards. Since standard enamelling steel is magnetically attractive, it may also be used for magnet boards. Some new developments in the last ten years include enamel/non-stick hybrid coatings, sol-gel functional top-coats for enamels, enamels with a metallic appearance, and easy-to-clean enamels. The key ingredient of vitreous enamel is finely ground glass called frit. Frit for enamelling steel is typically an alkali borosilicate glass with a thermal expansion and glass temperature suitable for coating steel. Raw materials are smelted together between into a liquid glass that is directed out of the furnace and thermal shocked with either water or steel rollers into frit. Colour in enamel is obtained by the addition of various minerals, often metal oxides

cobalt Cobalt is a chemical element; it has Symbol (chemistry), symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. ...

, praseodymium,

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

, or

neodymium Neodymium is a chemical element; it has Symbol (chemistry), symbol Nd and atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth element, rare-earth metals. It is a hard (physics), hard, sli ...

. The latter creates delicate shades ranging from pure violet through wine-red and warm grey. Enamel can be transparent, opaque or opalescent (translucent). Different enamel colours can be mixed to make a new colour, in the manner of paint. There are various types of frit, which may be applied in sequence. A ground coat is applied first; it usually contains smelted-in transition metal oxides such as cobalt, nickel, copper, manganese, and iron that facilitate adhesion to the metal. Next, clear and semi-opaque frits that contain material for producing colours are applied. File:Anker1-comp.jpg, View into a glass-lined chemical reactor File:Turborührer.jpg, Turb-mixer in a glass-lined chemical reactor

Techniques of artistic enameling

British Museum -Dunstable Swan Jewel -side cropped close

The three main historical techniques for enamelling metal are: *

Cloisonné Cloisonné () is an ancient technology, ancient technique for decorating metalwork objects with colored material held in place or separated by metal strips or wire, normally of gold. In recent centuries, vitreous enamel has been used, but inla ...

, French for "cell", where thin wires are applied to form raised barriers, which contain different areas of (subsequently applied) enamel. Widely practiced in Europe, the Middle East and East Asia. * Champlevé, French for "raised field", where the surface is carved out to form pits in which enamel is fired, leaving the original metal exposed; the Romanesque Stavelot Triptych is an example. * Painted enamel, a design in enamel is painted onto a smooth metal surface.

is the best known type of painted enamel, using this from the 16th century onwards. Most traditional painting on glass, and some on ceramics, uses what is technically enamel, but is often described by terms such as "painted in enamels", reserving "painted enamel" and "enamel" as a term for the whole object for works with a metal base. Variants, and less common techniques are: * Basse-taille, from the French word meaning "low-cut". The surface of the metal is decorated with a low relief design which can be seen through translucent and transparent enamels. The 14th century Royal Gold Cup is an outstanding example. * Plique-à-jour, French for "open to daylight" where the enamel is applied in cells, similar to cloisonné, but with no backing, so light can shine through the transparent or translucent enamel. It has a stained-glass like appearance; the Mérode Cup is the surviving medieval example. * Ronde bosse, French for "in the round", also known as "encrusted enamel". A 3D type of enamelling where a sculptural form or wire framework is completely or partly enamelled, as in the 15th century Holy Thorn Reliquary. *

Grisaille Grisaille ( or ; , from ''gris'' 'grey') means in general any European painting that is painted in grey. History Giotto used grisaille in the lower registers of his frescoes in the Scrovegni Chapel in Padua () and Robert Campin, Jan van Ey ...

, version of painted enamel, French term meaning "in grey", where a dark, often blue or black background is applied, then a palescent (translucent) enamel is painted on top, building up designs in a monochrome gradient, paler as the thickness of the layer of light colour increases.Lucie-Smith, 83 * En résille (, French for 'enamel in a network on glass') where enamelled metal is suspended in glass. The technique was briefly popular in seventeenth-century France and was re-discovered by Margret Craver in 1953. Craver spent 13 years re-creating the technique. Other types: *

Enamelled glass Enamelled glass or painted glass is glass which has been decorated with vitreous enamel (powdered glass, usually mixed with a binder) and then fired to glass fusing, fuse the glasses. It can produce brilliant and long-lasting colours, and be tr ...

, in which a glass surface is enamelled, and fired to fuse the glasses. *

Stencil Stencilling produces an image or pattern on a surface by applying pigment to a surface through an intermediate object, with designed holes in the intermediate object. The holes allow the pigment to reach only some parts of the surface creatin ...

ing, where a stencil is placed over the work and the powdered enamel is sifted over the top. The stencil is removed before firing, the enamel staying in a pattern, slightly raised. *

Sgraffito (; ) is an artistic or decorative technique of scratching through a coating on a hard surface to reveal parts of another underlying coating which is in a contrasting colour. It is produced on walls by applying layers of plaster tinted in con ...

, where an unfired layer of enamel is applied over a previously fired layer of enamel of a contrasting colour, and then partly removed with a tool to create the design. * Serigraph, where a silkscreen is used with 60–70in grade mesh. * Surrey enamel, a 17th-century type for brass objects such as candlesticks; effectively champlevé. * Counter-enamelling, not strictly a technique, but a necessary step in many techniques, especially painted enamel on thin plaques; introduced in 15th-century Europe. Enamel is applied to the back of a piece as well – sandwiching the metal – to equalize the rates of expansion under heat, and so create less tension on the glass so it does not crack. * Safed chalwan, where jewels are set in white enamel See also Japanese shipōyaki techniques.

Industrial enamel application

On sheet steel, a ground coat layer is applied to create adhesion. The only surface preparation required for modern ground coats is degreasing of the steel with a mildly alkaline solution. White and coloured second "cover" coats of enamel are applied over the fired ground coat. For electrostatic enamels, the coloured enamel powder can be applied directly over a thin unfired ground coat "base coat" layer that is co-fired with the cover coat in a very efficient two-coat/one-fire process. The frit in the ground coat contains smelted-in cobalt and/or nickel oxide as well as other transition metal oxides to catalyse the enamel-steel bonding reactions. During firing of the enamel at between , iron oxide scale first forms on the steel. The molten enamel dissolves the iron oxide and precipitates cobalt and

nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

. The iron acts as the anode in an electrogalvanic reaction in which the iron is again oxidised, dissolved by the glass, and oxidised again with the available cobalt and nickel limiting the reaction. Finally, the surface becomes roughened with the glass anchored into the holes.

Building cladding

Enamel coatings applied to steel panels offer protection to the core material whether cladding road tunnels, underground stations, building superstructures or other applications. It can also be specified as a curtain walling. Qualities of this structural material include: * Durable * Withstands extreme temperatures and is non-flammable * Long lasting UV, climate and corrosion resistance * Dirt-repellent and graffiti-proof * Resistant to abrasion and chemicals * Easy cleaning and maintenance

Gallery

File:Box holy oils Louvre OA6935.jpg, Early 13th century Limoges

chasse A chasse, châsse or box reliquary is a shape commonly used in medieval metalwork for reliquaries and other containers. To the modern eye the form resembles a house, though a tomb or church was more the intention,Distelberger, 21 with an obl ...

used to hold holy oils; most were

. File:Silver, silver gilt and painted enamel beaker, Burgundian Netherlands, c. 1425-1450, The Cloisters.JPG, Silver, silver gilt and painted enamel beaker,

Burgundian Netherlands The Burgundian Netherlands were those parts of the Low Countries ruled by the Dukes of Burgundy during the Burgundian Age between 1384 and 1482. Within their Burgundian State, which itself belonged partly to the Holy Roman Empire and partly t ...

, c. 1425–1450, The Cloisters, nyc File:British Museum Royal Gold Cup.jpg, The Royal Gold Cup with ''basse-taille'' enamels; weight 1.935 kg,

British Museum The British Museum is a Museum, public museum dedicated to human history, art and culture located in the Bloomsbury area of London. Its permanent collection of eight million works is the largest in the world. It documents the story of human cu ...

. Saint Agnes appears to her friends in a vision. File:Normandie Manche Avranches3 tango7174.jpg, Limoges? grisaille painted

Stations of the Cross The Stations of the Cross or the Way of the Cross, also known as the Via Dolorosa, Way of Sorrows or the , are a series of fourteen images depicting Jesus in Christianity, Jesus Christ on the day of Crucifixion of Jesus, his crucifixion and acc ...

, Notre-Dame-des-Champs, Avranches File:Musée Châlons-St Grégoire edit 3.jpg, St.

Gregory the Great Pope Gregory I (; ; – 12 March 604), commonly known as Saint Gregory the Great (; ), was the 64th Bishop of Rome from 3 September 590 until his death on 12 March 604. He is known for instituting the first recorded large-scale mission from Rom ...

in painted Limoges enamel on a copper plaque, by Jacques I Laudin File:Enamel 2.jpg, A freehand enameled painting by Einar Hakonarson. ''In the forest,'' 1989 File:Louis George Feuer-Emaille-Zifferblatt 01.jpg, '' Louis George'' enamel watch dial File:Iranian vitreous enamel.JPG, Iranian enamel

Notes

References

* Campbell, Marian. ''An Introduction to Medieval Enamels'', 1983,

HMSO The Office of Public Sector Information (OPSI) is the body responsible for the operation of His Majesty's Stationery Office (HMSO) and of other public information services of the United Kingdom. The OPSI is part of the National Archives of the U ...

for V&A Museum, * Lucie-Smith, Edward, ''The Thames & Hudson Dictionary of Art Terms'', 2003 (2nd edn), Thames & Hudson, World of Art series, *Ogden, Jack, "Metal", in ''Ancient Egyptian Materials and Technology'', eds. Paul T. Nicholson, Ian Shaw, 2000, Cambridge University Press, , 9780521452571
google books
*Osborne, Harold (ed), ''The Oxford Companion to the Decorative Arts'', 1975, OUP,

External links

Enamels on jewelry
– historical
Enameling Articles and Tutorials at The Ganoksin Project

CIDAE Center of Information and Difusion of the Art of Enamelling (ES)

Society of Dutch Enamellers (NL)

The Enamelist Society (US)

Guild of Enamellers, UK

International Enamellers Institute

Vitreous Enamel Association (UK)
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