Lueforgyldning
Lueforgyldning er den ældst kendte forgyldningsmetode, som blandt andet anvendes på dansk kirkesølv. Den giver en smuk sart guldoverflade på sølvet.
Historisk
Grunden til, at man véd, at lueforgyldning er den ældst kendte metode, er, at der ved lueforgyldning altid vil være en rest af kviksølv i forgyldningen, og at metoden derved kan genkendes.
På grund af kviksølvdampene kunne en forgylder altid kendes på symptomerne på en kviksølvforgiftning og på den hjerneskade, som kviksølvdampene giver. (Kunne dog forveksles med en hattemager, der ofte led af de samme sygdomme.)
Til store forgyldningsarbejder fik livstidsfanger tilbuddet om at arbejde som forgyldere, da det ellers var svært at rekruttere det antal forgyldere, som opgaven krævede.
ADVARSEL: Kviksølv er meget giftigt, og især kviksølvdampe er farlige og giver alvorlige hjerneskader selv ved begrænset eksponering! Alle områder, der udsættes for kviksølvdampe, forurenes permanent.
Processen
Forgyldningen udføres ved, at en pasta (amalgam) bestående af krystalliseret guld og kviksølv smøres på den overflade, der skal forgyldes. Herefter fjernes kviksølvet ved fordampning med en blød flamme (lue). Kviksølvet inddampes og kan recirkuleres.
Fremstilling af pasta
Guld og kviksølv kan ikke legeres ved opvarmning, da kviksølvs kogepunkt (356,58º C) er lavere end guldets smeltepunkt (1064,18° C).
24 karat guld fint granuleret bladguld stødes ned i kviksølv i en morter i forholdet 1:8, til en homogen pasta. Dette foretages under vand for at minimere eksponeringen med kviksølvdampe. Processen kan fremskyndes, hvis der iblandes noget guld og kviksølv, der har været opbevaret sammen i en periode, hvorved det spontant har dannet krystaller.
Pastaen opvarmes til 290° C, og under den efterfølgende afkøling dannes krystaller, hvor 2 guldatomer binder sig til 3 kviksølvatomer. Disse krystaller vil flyde i det overskydende kviksølv. Dette presses ud af pastaen ved at omvride pastaen i et stykke vaskeskind.
Påføring af pasta
Den afrensede sølvoverflade påsmøres pastaen med en lille spartel. Pastaen vil kunne bredes ud over sølvet.
Selve lueforgyldningen
Genstanden opvarmes jævnt og langsomt, og kviksølvet begynder at fordampe (LÆS ADVARSEL). Guldet vil binde sig til sølvet ved, at en ganske lille mængde kviksølv bliver tilbage og fungerer som bindemiddel.
Se også
Kilder og henvisninger
- Nielsen, H.C.; Thisted, I.O.; Weimar, Bjarne, red. (1948), Guldsmedebogen, København: Teknologisk Instituts Forlad, s. 178
- Hinnerup, P.R. (1839), Haandbog for Juvelere, Guld- og Sølvarbeidere, Eget Forlag, s. 537-545
- Cellini, Benvenetu (1967), "XXVI. How to gild", The Treatises of Benvenuto Cellini on Goldsmithing and Sculpture, oversat af Ashbee, C.R., New York: Dover Publications, ISBN 0-486-21568-7
Medier brugt på denne side
Forfatter/Opretter: John Jason Junior, Licens: CC0
French mantel clock (pendulum clock) with mercurial gilding (ormolu) in the shape of an amphora (around 1800) by Julien Béliard (born 1758 – died after 1806). The clockwork signed with a B for Béliard. Julien-Antoine Béliard, who always signed Julien Béliard on the dial, was one of the most important watchmakers of the late 18th century in Paris. He received his training in his father's workshop on the Rue de Hurepoix. On 21 October 1786, he was appointed Maître Horloger and then took over the family workshop. Béliard achieved great success and worked with some of the most renowned artisans of his time, including the bronze casters Claude Galle (1758–1815) and Nicolas Bonnet (1740–1789) and the enameller Joseph Coteau (1740–1812). Mantle clocks made by Julien Béliard are part of the collection of the Louvre Museum in Paris.
Literature: Pierre Kjellberg – Encyclopédie de La Pendule Française du Moyen Age au XX siècle, Les Éditions de l'Amateur, Paris, 1997.
The clock case of this clock is by Claude Galle (1758–1815). It is richly decorated with symbols from the Greek mythology:
Dial (flanking) – The goddess of victory Nike: On both sides of the dial, two identical mirrored sculptural winged goddess figures catch the eye. They are dressed in Greek robes, one of which has the crescent moon in her hair decoration, which symbolizes fertility, in connection with ebb and flow, as well as the changing of the seasons – and the other has a star in her hair decoration, which symbolizes the divine presence in general, but also light in the darkness and thus symbolizes hope and eternity. This is a double representation of the Greek goddess of victory Nike, each with an outstretched arm pointing to two crossed branches above the Roman numeral XII on the dial. The two crossed branches, a laurel and a palm branch, represent victory (laurel branch) and peace (palm branch).
Amphora Neck – The Four Seasons: The neck of the amphora is decorated with four putti, which represent an allegory of the four seasons (with reference to the above-mentioned representation of the goddess of victory Nike with the crescent moon in her hair ornament, symbolizing the change of the seasons): 1) Sowing in spring, 2) The harvest of grain in summer, 3) The grape harvest in autumn and 4) The burning of a fire in winter.
Handle of the amphora – vines and Bacchus, the god of wine: The handles of the amphora, the vessel for storing wine in ancient Greece, which are finely decorated with vine tendrils, emerge from a bearded man's head, representing the Greek god of wine, Bacchus. The handles end in coils with an owl's head, the symbol of wisdom in Greek mythology. The owl is also considered the favorite bird of the Greek goddess Athena and therefore the protector of the city of Athens. Under the dial there is a laurel wreath, the symbol of victory, which is held by a ribbon and closed at the top by a rose petal, which in Greek mythology symbolizes the feelings of love, passion and beauty, i.e. the attributes of the Greek goddess Aphrodite.
Foot of the amphora – laurel and Eros, god of love: The transition from the amphora body with the dial to the foot of the amphora is chased with fine patterns. The foot of the amphora is surrounded by a frieze of laurel leaves. The base, decorated with palmettes and Greek ornaments such as those found in the frieze of ancient Greek buildings, rests on a square base with flattened, crushed ball feet. On the front frieze of the base is a framed Eros, the Greek god of love, resting on a cushion, with his attributes, a bow and an arrow, and holding a rosary symbolizing love in his hand.