Gilder
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Gilding is the job title of a trade that deals with the refinement and design of surfaces of all kinds, for example by mechanically applying gold leaf and other metal leaf to metallic and non-metallic carrier materials.
The craft of gilding emerged from the painting trade and deals with the gilding and bronzing of building, room and furnishing elements, the gilding of sculptures, surface decorations and outdoor advertising. In addition, the surfaces to be processed are artistically designed with high and low reliefs, for example by the production of decorations, engravings, ground or chalk application and other techniques. The craft also deals with the gilding of paper , parchment , leather , textiles and glass . Mainly two techniques are used in the practice of the profession: the poliment gilding and the oil gilding.
Chemical types of gold plating, such as electrolysis from a gold salt solution (see electroplating ) or fire gold plating by evaporation of mercury from an applied gold amalgam, do not usually belong to the field of activity of a gold plater .
Early sources
Gilding leaf has been known since ancient times. In Egyptian graves, well-preserved gilding can be found on coffins, mummies, etc. There are no traces of the Greek gilding, but it is known from written sources that gilding was common practice, e.g. B. in the design of private and public buildings, in ornamentation, on statues, etc.
Pliny reports on the Roman gilding . It is the first to provide information on the technique of gilding in antiquity. “On marble and those objects that cannot be annealed, the gold is attached with the white of the egg, on wood with a glue-like mixture called leucophorone”. The following recipe shows that this is poliment gold plating . In the early centuries after Christ, oil gilding then developed.
Extensive sources are available from the late Roman imperial era as well as the Byzantine Empire and the subsequent Middle Ages, in which detailed information on all common techniques is given. Gold plating was widely used during this period, e.g. B. in book illumination .
Poliment gilding
Poliment gold plating or poliment gloss gold plating is only used indoors, as its technical structure does not provide any protection against moisture. This type of gilding is unique, as surfaces are created with a four-thousandth of a millimeter thick gold leaf that are indistinguishable from solid gold. The most common application in the early days was to decorate altars and Christian figures, then it was used for elaborate picture frames over the years . The first gilding of picture frames came in the Gothic period, when ornaments were gilded on the water hammer, and culminated in the gilding of magnificent Louis XIII frames.
A chalk base made of champagne chalk or Bolognese chalk , which is bound with organic glue , serves as a support for the poliment gilding . This chalk base is applied in several layers, usually 4 to 8 layers, but sometimes up to 20. The number of layers depends on the further processing. The polishing ability increases the more chalk ground is applied. In addition, many chalk grounds are required if the gilding is to be hallmarked after the gold plating has been completed. It is very important that the glue concentration decreases with each layer (build up lean on fat). This results in less surface tension during drying. This procedure must be taken into account for the entire structure. The poliment is spread on the dried and then sanded chalk ground. A fine bolus, usually red, yellow or gray-blue, is used for this purpose. This clay is now called poliment after it has been prepared with Venetian soap (a soap based on olive oil) and organic glue (usually hide glue) or egg white. After the poliment spread has been applied and dried, the area that is now to be gilded is moistened with the "nets" (water and 15 to 30 percent ethanol, in earlier times also brandy). Distilled water should be used to avoid limescale stains on the finished gold plating. The gold is applied with a pincer or earlier “shot” with the bilboquet into the area moistened with nets. It is called 'shot' because the net has a very low surface tension and thus the gold leaf suddenly shoots at the liquid. A flat brush is referred to as a slider. When processing gold leaf, it usually consists of squirrel hair mounted between two strips of cardboard. When shooting real silver, a shooter is also used, but with much thicker hair. The shooter is lightly greased. Different greases are used depending on the leaf metal to be processed. In the case of gold leaf, it is common to lightly grease the pin by stroking the cheek or the hair on the head; with silver leaf, a very good result is achieved with petroleum. After the entire surface has been gilded in this way and then dried through, the gold can be brought to a high gloss with a polishing stone .
Oil gilding
Oil gilding is used on stone, metal, textiles and outdoors. Like poliment gold plating, it cannot be polished, but unlike it, it is weatherproof. The preparation of the ground is limited to an oil coating, which dries over time before the gold is "shot". The application oil ( Mixtion ) is an oil that dries up slowly without tackiness and is made from linseed oil , black lead (PbO) and turpentine oil .
More techniques
Further techniques are mordent gilding (based on wax), gilding with egg white and with gelatine (gilding behind glass). The metals used are gold, colored gold, silver as well as aluminum, tin, bronze and other copper alloys.
application
The craft is mainly used in the restoration of old works of art and architectural parts as well as in the production of picture frames and the design of books and advertising space.
status
In November 2017, UNESCO added the profession of “gilding and staffing” to the list of traditional handicrafts in Austria .
See also
Individual evidence
- ↑ Vocational training in Germany follows the requirements of the Ordinance on Vocational Training for Gilders (GoldAusbV) of May 26, 1997 ( Federal Law Gazette I p. 1241 )
- ↑ In order to acquire the master's title in Germany, the requirements according to the regulation on the professional profile and on the examination requirements in the practical and in the theoretical part of the master craftsman's examination for the gilding trade (Gilding Master Ordinance - VergMstrV) of February 12, 1990 ( Federal Law Gazette I p. 283 ) must be observed.
- ↑ Austrian UNESCO Commission : Traditional handicrafts throughout Austria, gilding & staffing , UNESCO.AT website, accessed on April 4, 2018