Vitreous enamel: Difference between revisions

[[File:0 Reliquaire grandmontain - MR 2648 - Louvre (1).JPG|thumb|[[Gothic art|Gothic]] [[chasse (casket)|châsse]]; 1185–1200; champlevé enamel over copper gilded; height: {{cvt|17.7 |cm|in}}, width: {{cvt|17.4 |cm|in}}, depth: {{cvt|10.1 |cm |in}}]]

'''Vitreous enamel''', also called '''porcelain enamel''', is a material made by [[melting|fusing]] powdered [[glass]] to a substrate by firing, usually between {{convertcvt|750|and|850|C|F}}. The powder melts, flows, and then hardens to a smooth, durable [[vitrification|vitreous]] coating. The word ''vitreous'' comes from the Latin {{wikt-lang|la|vitreumvitreus}}, meaning "glassglassy".

[[File:明早期 掐絲琺瑯菱花口碟-Dish with scalloped rim MET DT7072 (cropped).jpg|thumb|[[Chinese art|Chinese]] dish with scalloped rim, from the [[Ming Dynastydynasty]]; early 15th century; [[cloisonné]] enamel; height: 2.5 cm, diameter: 15.2 cm]]

Enamelling is an old and widely adopted technology, for most of its history mainly used in [[jewellery]] and [[decorative art]]. 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]] bathtubs. It has also been used on some [[Major appliance|appliances]], such as dishwashers[[dishwasher]]s, [[laundry machinesmachine]]s, and refrigerators[[refrigerator]]s, and on marker boards and [[enamel sign|signage]].

The technique appears in the [[Koban culture|Koban]] culture of the northern and central [[Caucasus]], and was perhaps carried by the [[Sarmatians]] to the ancient Celts.<ref name="Osborne, 331"/> Red enamel is used in 26 places on the [[Battersea Shield]] (c.350–50 BC), probably as an imitation of the red Mediterranean [[coral]], which is used on the [[Witham Shield]] (400-300400–300 BC). [[Pliny the Elder]] 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]], 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 bowl]]s of early [[Anglo-Saxon art]].

In European art history, enamel was at its most important in the [[Middle Ages]], beginning with the Late Romans and then the [[Byzantine Empire|Byzantine]], who began to use [[cloisonné]] enamel in imitation of cloisonné inlays of precious stones. The [[Byzantine enamel]] style was widely adopted by the peoples of [[Migration Period]] northern Europe. The Byzantines then began to use cloisonné more freely to create images; this was also copied in Western Europe. In [[Kievan Rus]] a [[finift enamel]] technique was developed.<ref>{{Citation |title=ХУДОЖНЯ ЕМАЛЬ У ХРОНОТОПІ УКРАЇНСЬКОГО МИСТЕЦТВА. Альманах |last=Наумов |first=Олег |date=2019-01-01 |work=Культура і Сучасність |volume=2019 |issue=2 |pages=192–197}}</ref><ref name =Mostovshchikova2020>{{Citation |title=Traditions of painted hot enamel of Europe and the East of the XVIIIth century in contemporary enamel art of Ukraine |last=Мостовщикова |first=Дар'я Олегівна |url=https://elibrary.kubg.edu.ua/id/eprint/32111/ |journal=Актуальнi питання гуманiтарних наук: Мiжвузiвський збiрник наукових праць молодих вчених Дрогобицького державного педагогiчного унiверситету iменi Iвана Франка |volume=1 |year=2020|issue=30 |pages=173–180|doi=10.24919/2308-4863.1/30.212240 }}</ref>

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[[inkwell]]s and in small portraits. After it fell from fashion it continued as a medium for [[portrait miniature]]s, spreading to England and other countries. This continued until the early 19th century.

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".<ref name=Sullivan>Sullivan, Michael, ''The arts of China'', 4th edn, p.&nbsp;239, University of California Press, 1999, {{ISBN|0-520-21877-9}}, {{ISBN|978-0-520-21877-2}}, [https://books.google.com/books?id=sn0CyBCJKz8C&pg=PA239 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]] (1425–351425–1435), 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 Dynastydynasty]], especially the reigns of the Xuande Emperor and [[Jingtai Emperor]] (1450–571450–1457), although 19th century or modern pieces are far more common.<ref name=Sullivan />

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 (era)|Meiji]] and [[Taishō]] eras (late 19th/ early 20th century).<ref name="enamelinjapan">{{cite book |last1=Impey |first1=Oliver |last2=Fairley |first2=Malcolm |editor1-last=Williams |editor1-first=Haydn |title=Enamels of the world, 1700-2000: the Khalili collections |date=2009 |publisher=Khalili Family Trust |location=London |isbn=978-1-874780-17-5 |pages=149–156 |chapter=Enamel in Japan}}</ref> Enamel had been used as decoration for metalwork since about 1600,<ref name="earle">{{Cite book|last=Earle|first=Joe|title=Splendors of Meiji : treasures of imperial Japan : masterpieces from the Khalili Collection|publisher=Broughton International Inc|year=1999|isbn=1874780137|location=St. Petersburg, Fla.|pages=252–254|oclc=42476594}}</ref><ref name="enamelinjapan" /> and Japanese cloisonné was already exported to Europe before the start of the Meiji era in 1868.<ref name="enamelinjapan" /> Cloisonné is known in Japan as {{lang|ja-latn|shippo}}, literally "seven treasures".<ref>{{Cite journal|last=Harada|first=Jiro|date=1911|title=Japanese Art & Artists of To-day VI. Cloisonné Enamels|url=https://archive.org/details/studiointernatio53lond/page/270/mode/2up|journal=The Studio|volume=53|page=271|via=Internet Archive}}</ref> This refers to richly coloured substances mentioned in Buddhist texts.<ref name="polished">{{Cite web|date=5 November 2017|title=Polished to Perfection|url=https://asianartnewspaper.com/polished-to-perfection/|access-date=16 July 2020|website=Asian Art Newspaper|issn=1475-1372}}</ref> 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.<ref name="polished" /><ref name="earle" />

Enamel was used in [[Iran]] 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]], 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]], a later introduction, is used for artifacts like boxes, bowls, spoons, and art pieces. [[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. 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.<ref>{{cite web|url=http://www.iranreview.org/content/Documents/The_Art_of_Minakari_2.htm|title=The Art of Minakari|website=iranreview.org}}</ref>

More recently, the bright, jewel-like colours have made enamel apopular favoured choice forwith jewellery designers, including the [[Art Nouveau]] jewellers, for designers of [[wikt:bibelot|bibelots]] such as the eggs of [[Peter Carl Fabergé]] and the enameled copper boxes of the Battersea enamellers,<ref>{{cite web|url=http://www.vea.org.uk/what-is-enamel/|title=What is Vitreous Enamel?|website=vea.org.uk}}</ref> and for artists such as [[George Stubbs]] and other painters of [[portrait miniature]]s.

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]],<ref>Judd, Donald, “Porcelain Enameling Aluminum: An Overview,” Proceedings of the 59th Porcelain Enamel Institute Technical Forum, 45-51 (1997).</ref> stainless steel,<ref>Sullivan, J.D. and Nelson, F.W., "Stainless Steel Requires Special Enameling Procedures", Proceedings of the Porcelain Enamel Institute Technical Forum," 150-155150–155 (1970).</ref> and [[cast iron]].<ref>Pew, Steve, "The Who, What, Why, Where, and When of Cast Iron Enameling," Advances in Porcelain Enamel Technology, 177-186177–186, (2010).</ref>

Vitreous enamel has many useful properties: it is smooth, hard, chemically resistant, durable, scratch resistant (5–6 on the [[Mohs_scale_of_mineral_hardnessMohs scale of mineral hardness|Mohs scale]]), 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]].<ref>Fedak, David and Baldwin, Charles, "A Comparison of Enameled and Stainless Steel Surfaces," Proceedings of the 67th Porcelain Enamel Institute Technical Forum, 45-54 (2005).</ref> 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]] well-matched to the metal.{{Citation needed|date=March 2024}}

The Buick automobile company was founded by [[David Dunbar Buick]] 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]] signs, interior [[oven]] walls, [[cooking pot]]s, housing and interior walls of major [[kitchen appliance]]s, housing and drums of clothes washers and dryers, sinks and [[cast iron]] [[bathtub]]s, [[farm]] [[storage silo]]s, and processing equipment such as [[chemical reactor]]s and pharmaceutical process tanks. Structures such as [[filling station]]s, [[bus station]]s and [[Lustron House]]s had walls, ceilings and structural elements made of enamelled steel.{{Citation needed|date=March 2024}}

* The three main historical techniques for enamelling metal are:

** [[Cloisonné]], 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.<ref>Campbell, 6, 10-17</ref>

** [[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.<ref>Campbell, 7, 17-32</ref>

** Painted enamel, a design in enamel is painted onto a smooth metal surface. [[Limoges enamel]] is the best known type of painted enamel, using this from the 16th century onwards.<ref>Campbell, 7</ref> 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.<ref>[https://www.britishmuseum.org/research/search_the_collection_database/term_details.aspx?scopeType=Terms&scopeId=17395 British Museum] collection database, "Scope note" for the term "enamelled"; other sources use different categories.</ref>

** [[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.<ref>Campbell, 7, 33-41</ref>

** [[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.<ref>Campbell, 38-42</ref>

*** [[Grisaille]], 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.<ref name="Lucie-Smith, 83">Lucie-Smith, 83</ref>

* [[En résille]] ({{Lang|fr|Émail en résille sur verre}}, 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.<ref>{{cite web|url=http://www.americanart.si.edu/luce/object.cfm?key=338&artistmedia=0&subkey=330|archive-url=https://web.archive.org/web/20090713051944/http://www.americanart.si.edu/luce/object.cfm?key=338&artistmedia=0&subkey=330|url-status=dead|archive-date=13 July 2009|title=Craft: Jewelry: Brooch|work=Luce Foundation Center for American Art|publisher=Smithsonian American Art Museum|access-date=29 March 2013}}</ref>

*Other types:

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

* '''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.<ref> name="Lucie-Smith, 83<"/ref>

* See also [[Ando Cloisonné Company#Types|Japanese shipōyaki techniques]].

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 {{convert|760|toand|895|C|F}}, iron oxide scale first forms on the steel. The molten enamel dissolves the iron oxide and precipitates cobalt and [[nickel]]. 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.<ref>Feldman, Sid and Baldwin, Charles, "Surface Tension and Fusion Properties of Porcelain Enamels," Proceedings of the 69th Porcelain Enamel Institute Technical Forum, 1-10 (2008)</ref>

* [[Fred Uhl Ball]] (1945–1985) – American enamellist who created the largest known enamel mural

* [[Rostov, Yaroslavl Oblast|Rostov]] in Russia, with Moscow a centre of the Russian industry

*[[Edward Lucie-Smith| Lucie-Smith, Edward]], ''The Thames & Hudson Dictionary of Art Terms'', 2003 (2nd edn), Thames & Hudson, World of Art series, {{ISBN|0500203652}}

*Ogden, Jack, "Metal", in ''Ancient Egyptian Materials and Technology'', eds. Paul T. Nicholson, Ian Shaw, 2000, Cambridge University Press, {{ISBN|0521452570}}, 9780521452571, [https://books.google.co.ukcom/books?id=Vj7A9jJrZP0C&pg=PA166 google books]