Gilding

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Gilded frame ready for burnishing with agate stone tool Gilded frame being burnished with agate tool.jpg
Gilded frame ready for burnishing with agate stone tool
Application of gold leaf to a reproduction of a 15th-century panel painting

Gilding is a decorative technique for applying a very thin coating of gold to solid surfaces such as metal (most common), wood, porcelain, or stone. A gilded object is also described as "gilt". Where metal is gilded, it was traditionally silver in the West, to make silver-gilt (or vermeil) objects, but gilt-bronze is commonly used in China, and also called ormolu if it is Western. Methods of gilding include hand application and gluing, typically of gold leaf, chemical gilding, and electroplating, the last also called gold plating. [1] Parcel-gilt (partial gilt) objects are only gilded over part of their surfaces. This may mean that all of the inside, and none of the outside, of a chalice or similar vessel is gilded, or that patterns or images are made up by using a combination of gilt and ungilted areas.

Contents

Gilding gives an object a gold appearance at a fraction of the cost of creating a solid gold object. In addition, a solid gold piece would often be too soft or too heavy for practical use. A gilt surface also does not tarnish as silver does.

Origins and spread

A gilded Tibetan Vajrasattva Vajrasattva Tibet.jpg
A gilded Tibetan Vajrasattva

Herodotus mentions that the Egyptians gilded wood and metals, and many such objects have been excavated. Certain Ancient Greek statues of great prestige were chryselephantine, i.e., made of gold (for the clothing) and ivory (for the flesh); these however, were constructed with sheets of gold over a timber framework, not gilded. Extensive ornamental gilding was also used in the ceiling coffers of the Propylaea. Pliny the Elder informs us that the first gilding seen at Rome was after the destruction of Carthage, under the censorship of Lucius Mummius, when the Romans began to gild the ceilings of their temples and palaces, the Capitol being the first place on which this process was used. But he adds that luxury advanced on them so rapidly that in very little time you might see all, even private and poor people, gild the walls, vaults, and other parts of their dwellings. Owing to the comparative thickness of the gold leaf used in ancient gilding, the traces of it that remain are remarkably brilliant and solid. Fire-gilding of metal goes back at least to the 4th century BC, and was known to Pliny (33,20,64–5), Vitruvius (8,8,4) and in the Early Mediaeval period to Theophilus (De Diversis Artibus Book III).

In Europe, silver-gilt has always been more common than gilt-bronze, but in China the opposite has been the case. The ancient Chinese also developed the gilding of porcelain, which was later taken up by the French and other European potters.

Processes

Modern gilding is applied to numerous and diverse surfaces and by various processes; those used in modern technology are described in gold plating. More traditional techniques still form an important part of framemaking and are sometimes still employed in general woodworking, cabinet-work, decorative painting and interior decoration, bookbinding, and ornamental leather work, and in the decoration of pottery, porcelain, and glass.

Mechanical

Regilding the statue Prometheus Gilding Rock Cen Prometheus jeh.jpg
Regilding the statue Prometheus
Gilded page edges on a book. Old book with gilded page edges.JPG
Gilded page edges on a book.

Mechanical gilding includes all the operations in which gold leaf is prepared, and the processes to mechanically attach the gold onto surfaces. The techniques include burnishing, water gilding and oil-gilding used by wood carvers and gilders; and the gilding operations of the house decorator, sign painter, bookbinder, the paper stainer and several others.

"Overlaying" or folding or hammering on gold foil or gold leaf is the simplest and most ancient method, and is mentioned in Homer's Odyssey (Bk vi, 232) [2] and the Old Testament. The Ram in a Thicket of about 2600–2400 BCE from Ur uses this technique on wood, with a thin layer of bitumen underneath to help adhesion.

The next advances involved two simple processes. The first involves gold leaf, which is gold that is hammered or cut into very thin sheets. Gold leaf is often thinner than standard paper today, and when held to the light is semi-transparent. In ancient times it was typically about ten times thicker than today, and perhaps half that in the Middle Ages.

If gilding on canvas or on wood, the surface was often first coated with gesso. "Gesso" is a substance made of finely ground gypsum or chalk mixed with glue. Once the coating of gesso had been applied, allowed to dry, and smoothed, it was re-wet with a sizing made of rabbit-skin glue and water ("water gilding", which allows the surface to be subsequently burnished to a mirror-like finish) or boiled linseed oil mixed with litharge ("oil gilding", which does not) and the gold leaf was layered on using a gilder's tip and left to dry before being burnished with a piece of polished agate. Those gilding on canvas and parchment also sometimes employed stiffly-beaten egg whites ("glair"), gum, and/or Armenian bole as sizing, though egg whites and gum both become brittle over time, causing the gold leaf to crack and detach, and so honey was sometimes added to make them more flexible.

Other gilding processes involved using the gold as pigment in paint: the artist ground the gold into a fine powder and mixed it with a binder such as gum arabic. The resulting gold paint, called shell gold, was applied in the same way as with any paint. Sometimes, after either gold-leafing or gold-painting, the artist would heat the piece enough to melt the gold slightly, ensuring an even coat. These techniques remained the only alternatives for materials like wood, leather, the vellum pages of illuminated manuscripts, and gilt-edged stock.[ citation needed ]

Chemical

Silver gilt toilette set by Johann Jacob Kirstein (1733-1816) in the Musee des Arts decoratifs, Strasbourg Johann Jacob Kirstein 001.JPG
Silver gilt toilette set by Johann Jacob Kirstein (1733–1816) in the Musée des Arts décoratifs, Strasbourg

Chemical gilding embraces those processes in which the gold is at some stage of chemical combination. These include:

Cold

In this process the gold is obtained in a state of extremely fine division, and applied by mechanical means. Cold gilding on silver is performed by a solution of gold in aqua regia, applied by dipping a linen rag into the solution, burning it, and rubbing the black and heavy ashes on the silver with the finger or a piece of leather or cork.

Wet

Wet gilding is effected by means of a dilute solution of gold(III) chloride in aqua regia with twice its quantity of ether. The liquids are agitated and allowed to rest, to allow the ether to separate and float on the surface of the acid. The whole mixture is then poured into a separating funnel with a small aperture, and allowed to rest for some time, when the acid is run off from below and the gold dissolved in ether separated. The ether will be found to have taken up all the gold from the acid, and may be used for gilding iron or steel, for which purpose the metal is polished with fine emery and spirits of wine. The ether is then applied with a small brush, and as it evaporates it deposits the gold, which can now be heated and polished. For small delicate figures, a pen or a fine brush may be used for laying on the ether solution. The gold(III) chloride can also be dissolved in water in electroless plating wherein the gold is slowly reduced out of solution onto the surface to be gilded. When this technique is used on the second surface of glass and backed with silver, it is known as "Angel gilding".

Fire

Fire-gilding or Wash-gilding is a process by which an amalgam of gold is applied to metallic surfaces, the mercury being subsequently volatilized, leaving a film of gold or an amalgam containing 13 to 16% mercury. In the preparation of the amalgam, the gold must first be reduced to thin plates or grains, which are heated red-hot, and thrown into previously heated mercury, until it begins to smoke. When the mixture is stirred with an iron rod, the gold is totally absorbed. The proportion of mercury to gold is generally six or eight to one. When the amalgam is cold, it is squeezed through chamois leather to separate the superfluous mercury; the gold, with about twice its weight of mercury, remains behind, forming a yellowish silvery mass with the consistency of butter.

When the metal to be gilded is wrought or chased, it ought to be covered with mercury before the amalgam is applied, that this may be more easily spread; but when the surface of the metal is plain, the amalgam may be applied to it directly. When no such preparation is applied, the surface to be gilded is simply bitten and cleaned with nitric acid. A deposit of mercury is obtained on a metallic surface by means of quicksilver water, a solution of mercury(II) nitrate, the nitric acid attacking the metal to which it is applied, and thus leaving a film of free metallic mercury.

The amalgam being equally spread over the prepared surface of the metal, the mercury is then sublimed by a heat just sufficient for that purpose; for, if it is too great, part of the gold may be driven off, or it may run together and leave some of the surface of the metal bare. When the mercury has evaporated, which is known by the surface having entirely become of a dull yellow color, the metal must undergo other operations, by which the fine gold color is given to it. First, the gilded surface is rubbed with a scratch brush of brass wire, until its surface is smooth.

It is then covered with gilding wax, and again exposed to fire until the wax is burnt off. Gilding wax is composed of beeswax mixed with some of the following substances: red ochre, verdigris, copper scales, alum, vitriol, and borax. By this operation the color of the gilding is heightened, and the effect seems to be produced by a perfect dissipation of some mercury remaining after the former operation. The gilt surface is then covered over with potassium nitrate, alum or other salts, ground together, and mixed into a paste with water or weak ammonia. The piece of metal thus covered is exposed to heat, and then quenched in water.

By this method, its color is further improved and brought nearer to that of gold, probably by removing any particles of copper that may have been on the gilt surface. This process, when skillfully carried out, produces gilding of great solidity and beauty, but owing to the exposure of the workmen to mercurial fumes, it is very unhealthy. There is also much loss of mercury to the atmosphere, which brings extremely serious environmental concerns as well.

This method of gilding metallic objects was formerly widespread, but fell into disuse as the dangers of mercury toxicity became known. Since fire-gilding requires that the mercury be volatilized to drive off the mercury and leave the gold behind on the surface, it is extremely dangerous. Breathing the fumes generated by this process can quickly result in serious health problems, such as neurological damage and endocrine disorders, since inhalation is a very efficient route for mercuric compounds to enter the body. This process has generally been supplanted by the electroplating of gold over a nickel substrate, which is more economical and less dangerous.

Depletion

In depletion gilding, a subtractive process discovered in Pre-columbian Mesoamerica, articles are fabricated by various techniques from an alloy of copper and gold, named tumbaga by the Spaniards. The surface is etched with acids, resulting in a surface of porous gold. The porous surface is then burnished down, resulting in a shiny gold surface. The results fooled the conquistadors into thinking they had massive quantities of pure gold. The results startled modern archaeologists, because at first the pieces resemble electroplated articles. Keum-boo is a special Korean technique of silver-gilding, using depletion gilding.

Ceramics

Buddha, 16th Century, gilt on wood. The Walters Art Museum. Korean - Buddha - Walters 61277.jpg
Buddha, 16th Century, gilt on wood. The Walters Art Museum.

The gilding of decorative ceramics has been undertaken for centuries, with the permanence and brightness of gold appealing to designers. Both porcelain and earthenware are commonly decorated with gold, and in the late 1970s it was reported that 5 tonnes of gold were used annually for the decoration of these products. [4] Some wall tiles also have gold decoration. [5] [6] Application techniques include spraying, brushing, banding machines, and direct or indirect screen-printing. [7] After application the decorated ware is fired in a kiln to fuse the gold to the glaze and hence ensure its permanence. The most important factors affecting coating quality are the composition of applied gold, the state of the surface before application, the thickness of the layer and the firing conditions. [8]

A number of different forms and compositions are available to apply gold to ceramic, and these include: [9] [10]

See also

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Mercury silvering

Mercury silvering or fire gilding is a silvering technique for applying a thin layer of precious metal such as silver or gold to a base metal object. The process was invented during the Middle Ages and is documented in Vannoccio Biringuccio's 1540 book De la pirotechnia. An amalgam of mercury and the precious metal is prepared and applied to the object which is then heated, sometimes in oil, vaporizing most of the mercury. The technique is dangerous since mercury is highly toxic, especially in its vapor phase. Mercury silvering can be detected through a variety of methods.

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Plating is a surface covering in which a metal is deposited on a conductive surface. Plating has been done for hundreds of years; it is also critical for modern technology. Plating is used to decorate objects, for corrosion inhibition, to improve solderability, to harden, to improve wearability, to reduce friction, to improve paint adhesion, to alter conductivity, to improve IR reflectivity, for radiation shielding, and for other purposes. Jewelry typically uses plating to give a silver or gold finish.

Tumbaga alloy

Tumbaga is the name for a non-specific alloy of gold and copper given by Spanish Conquistadors to metals composed of these elements found in widespread use in pre-Columbian Mesoamerica in North America and South America.

Verre églomisé

Verre églomisé is a French term referring to the process of applying both a design and gilding onto the rear face of glass to produce a mirror finish. The name is derived from the 18th-century French decorator and art-dealer Jean-Baptiste Glomy (1711–1786), who was responsible for its revival.

Ormolu

Ormolu is the gilding technique of applying finely ground, high-carat gold–mercury amalgam to an object of bronze, and for objects finished in this way. The mercury is driven off in a kiln leaving behind a gold coating. The French refer to this technique as "bronze doré"; in English, it is known as "gilt bronze". Around 1830, legislation in France had outlawed the use of mercury for health reasons, though use continued to the 1900s.

Silvering is the chemical process of coating a non-conductive substrate such as glass with a reflective substance, to produce a mirror. While the metal is often silver, the term is used for the application of any reflective metal.

Champlevé

Champlevé is an enamelling technique in the decorative arts, or an object made by that process, in which troughs or cells are carved, etched, die struck, or cast into the surface of a metal object, and filled with vitreous enamel. The piece is then fired until the enamel fuses, and when cooled the surface of the object is polished. The uncarved portions of the original surface remain visible as a frame for the enamel designs; typically they are gilded in medieval work. The name comes from the French for "raised field", "field" meaning background, though the technique in practice lowers the area to be enamelled rather than raising the rest of the surface.

Gold leaf art medium

Gold leaf is gold that has been hammered into thin sheets by goldbeating and is often used for gilding. Gold leaf is available in a wide variety of karats and shades. The most commonly used gold is 22-karat yellow gold.

Overglaze decoration

Overglaze decoration, overglaze enamelling or on-glaze decoration is a method of decorating pottery, most often porcelain, where the coloured decoration is applied on top of the already fired and glazed surface, and then fixed in a second firing at a relatively low temperature, often in a muffle kiln. It is often described as producing "enamelled" decoration. The colours fuse on to the glaze, so the decoration becomes durable. This decorative firing is usually done at a lower temperature which allows for a more varied and vidid palette of colours, using pigments which will not colour correctly at the high temperature necessary to fire the porcelain body. Historically, a relatively narrow range of colours could be achieved with underglaze decoration, where the coloured pattern is applied before glazing, notably the cobalt blue of blue and white porcelain.

Depletion gilding is a method for producing a layer of nearly pure gold on an object made of gold alloy by removing the other metals from its surface. It is sometimes referred to as a "surface enrichment" process.

Amalgam (chemistry) alloy of mercury with another metal

An amalgam is an alloy of mercury with another metal. It may be a liquid, a soft paste or a solid, depending upon the proportion of mercury. These alloys are formed through metallic bonding, with the electrostatic attractive force of the conduction electrons working to bind all the positively charged metal ions together into a crystal lattice structure. Almost all metals can form amalgams with mercury, the notable exceptions being iron, platinum, tungsten, and tantalum. Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore. Dentistry has used alloys of mercury with metals such as silver, copper, indium, tin and zinc.

Martin Pierce is a wood carver and furniture and hardware designer born in Worcester, England. It was here he began his career as a wood carver, working for businesses and churches in the surrounding area. He has been a resident of Los Angeles since 1980 and, during this period has developed several unique styles of furniture, which include his signature Hedgerow dining chair and Hedgerow bed. Other unique furniture styles include the Ascot and Seicho lines. Many of these pieces are japanned, or gilded, with vines and aspen trees and are part of a limited edition that is both numbered and signed.

Silver-gilt silver gilded with gold 14kt

Silver-gilt or gilded/gilt silver, sometimes known in American English by the French term vermeil, is silver which has been gilded with gold. Most large objects made in goldsmithing that appear to be gold are actually silver-gilt; for example most sporting trophies and many crown jewels are silver-gilt objects.

French Empire mantel clock decorated mantel clock made during the Napoleonic Empire

A French Empire-style mantel clock is a type of elaborately decorated mantel clock that was made in France during the Napoleonic Empire (1804–1814/15). Timekeepers manufacturing during the Bourbon Restoration (1814/1815–1830) are also included within this art movement as they share similar subjects, decorative elements, shapes, and style.

Angel gilding

Angel gilding is gilding glass or gold plating by electroless chemical deposition.

Pastiglia low relief decoration, normally modelled in gesso or white lead, applied to build up a surface that may then be gilded or painted, or left plain

Pastiglia[paˈstiʎʎa], an Italian term meaning "pastework", is low relief decoration, normally modelled in gesso or white lead, applied to build up a surface that may then be gilded or painted, or left plain. The technique was used in a variety of ways in Italy during the Renaissance. The term is mostly found in English applied to gilded work on picture frames or small pieces of furniture such as wooden caskets and cassoni, and also on areas of panel paintings, but there is some divergence as to the meaning of the term between these specialisms.

Conservation and restoration of painting frames

The conservation and restoration of painting frames is the process through which picture frames are preserved. Frame conservation and restoration includes general cleaning of the frame, as well as in depth processes such as replacing damaged ornamentation, gilding, and toning.

Gilders tip

A gilder's tip is a type of gilding brush used for transferring sheets of gold, silver, or other precious metal leaf to either a surface that has been prepared to accept the leaf or to a gilder's block where the leaf is then cut with a gilder's knife into smaller portions before being transferred to the prepared surface. The hairs on a gilder's tip are usually made of either blue squirrel hair or the hair of a badger arranged in a single or double row along a flat ferrule made of wood or cardboard. In order to transfer the gold leaf, the hairs are first given a very light coating of adhesive by brushing them against a surface such as the back of the user's hand which has been coated with a thin layer of petroleum jelly and then laying the edge of the brush along the edge of the piece of metal foil. The jelly will cause the metal to adhere very gently to the hairs and allow the piece to be floated from the paper surface on which had previously been stored. Because the leaf is so thin, this must be done in a room with extremely still air, and the user of the tip usually does not breathe until the leaf is in place. Once the leaf has settled, it is often burnished with polished piece of agate to achieve a high degree of brilliance.

References

  1. Sloan, Annie (1996) Decorative Gilding, Collins & Brown, ISBN   978-0-89577-879-6
  2. "And as when a man overlays silver with gold, a cunning workman whom Hephaestus and Pallas Athena have taught all manner of craft, and full of grace is the work he produces, even so the goddess shed grace upon his head and shoulders" from this translation
  3. "Buddha". The Walters Art Museum.
  4. Hunt, L. B. (1979). "Gold in the pottery industry". Gold Bulletin. 12 (3): 116–127. doi: 10.1007/BF03215112 .
  5. Etris, S.F. (1982). "Gold And Lustres For The Ceramic Tile Industry". Ceramic Industries. 119 (5): 36.
  6. Abt, K. (2008). "Comeback Of Gold Decoration? Trends And New Materials For Tile Decoration". Keram. Z. 60 (1).
  7. Groh, E. (1995). "Precious Metal Preparations: Composition, Applications And Special Decorative Effects". Ceramic Forum International. 72 (3).
  8. Gerasimova, L. V.; Ivanova, V. M.; Peskova, E. Yu.; Druzhinin, E. V. (1991). "Improving gold decorating techniques". Glass and Ceramics. 48 (11): 535. doi:10.1007/BF00676649.
  9. Dodd, A.and Murfin, D. (1994) Dictionary Of Ceramics. The Institute Of Minerals.
  10. Rovinskaya, N. V.; Lapitskaya, E. V. (1998). "Liquid gold and other components used in decoration of glazed porcelain and glass articles". Glass and Ceramics. 55 (3–4): 98. doi:10.1007/BF03180905.
  11. Helena Hayward (ed.) (1960) The Connoisseur’s Handbook of Antique Collecting. Galahad Books, NY.
  12. "Burnish Gold Decorating Composition." UK Pat.Appl.GB2216536 A, for Heraeus W.C., Gmbh.

Wikisource-logo.svg This article incorporates text from a publication now in the public domain : Chisholm, Hugh, ed. (1911). "Gilding". Encyclopædia Britannica . 11 (11th ed.). Cambridge University Press. pp. 13–14.

Further reading