Hobbies And Interests
Terms
Bronze gilding is also called "ormolu," the English word for the French term "or moulu," which means "ground gold," according to the website Antique Instruments. The term arose from the use of ground gold in the gilding.
History
The bronze sculptor Jacques Caffieri, who worked for King Louis XV, was the most famous designer in France to use ormolu, according to Antique Instruments.co.uk. Caffieri took the technique to new heights and even designed an ormolu toilet for the king's Versailles Palace. Unfortunately, many of his ormolu pieces disappeared during the French Revolution, when Versailles was sacked. In England the most famous ormolu was produced by Matthew Boulton of Birmingham in his Soho workshops between 1768 and 1782. The customers for his pieces included Queen Victoria and King George IV. The ornate ormolu clock produced by Boulton for King George IV was designed by William Chambers, the king's favorite architect, according to Antique Instruments.
Process
Gilding was the last step in the creation of gilt-bronze objects or furniture mounts, according to the Met Museum.org. In this process the bronze surface was coated with a mixture of ground gold and mercury and heated over an open fire. The process was repeated until a thick layer of gold was created, and the gold was either left matte or burnished using a heliotrope stone.
According to Robert L. Reese Antiques &Fine Art, mercury gilding was used because bronze smiths had to find a way to melt the gold onto the bronze surface without using too much costly gold and without re-heating the bronze work itself, which could cause melting or dulling of details. The mercury (liquid metal) and ground gold mixture could be applied with a wire brush, which avoided wasting gold. The work could also be heated at low temperatures, which were enough to turn the mercury into fumes and leave only the gold.
Hazards
The ormolu process was dangerous for craftsmen because of the fumes created when the mercury evaporated. According to Antique Instruments, few of them survived beyond the age of 40. A safer mixture of at least 50 percent copper with zinc and tin was later used, together with electro-plating methods. Gold was reserved for the finest pieces, but electro-plating used even less gold than the older ormolu process.
Significance
Due to legislation outlawing the use of mercury, true ormolu was no longer produced after about 1830, according to Antique Instruments.com. Starting in the mid-19th century, larger amounts of gilt bronze could be produced at low cost with the new electro gilding, according to Robert L. Reese Antiques &Fine Art, which explains the pricing difference between "Period" ormolu objects and later "Style of" objects using electro gilding.