The Features of Gilt Bronze Technique
Bronze accessories were not used much in the Renaissance, but they often appeared in the Baroque style. These accessories absorb the decorative patterns used in previous periods to be carved on wooden furniture, such as portraits, pillars, etc. These replicas are much smaller in size and are properly arranged on various types of furniture.
The best craftsman who used copper fittings during the time of Louis XIV was Andre-Charles Boulle. The accessories are either simply cast in bronze, or they are later added as bronzing. The most valuable technique is bronzing, which constituted the vast majority of 18th century copper accessories, and accounted for a large part of 19th century copper accessories.
There are different opinions on the origin of the bronzing process. Some can be traced back to the Middle Ages, or even to the ancient Roman era, some can be traced back to the 17th century, while others believe that this is a product of the Regency period.
As far as I concerned, I believe that this technology was widely known in the 17th century. However, regardless of its exact chronological order, bronzing technology was widely spread in the late 17th century, developed throughout the 18th century, and continued to be used throughout most of the 19th century. It is used alternately with electronic gilding, and until now we can all find its shadow in our lives.
We know that gold is the most malleable metal, and almost transparent gold foil can be obtained. The properties of gold require that it should be alloyed with other metals to obtain a consistency that can be processed. In mercury bronzing, amalgam must first be obtained. To do this, a certain amount of gold is poured into the heated mercury, and then the solution is poured on the bronze. The entire object is then heated to a temperature high enough to evaporate the mercury (about 430 degrees); so that the gold is fixed to the bronze and can be polished until shiny or matte.
Hot stamping is not the only known technique, but it is by far the best technique, especially the most durable technique. This technique keeps the color of gold unchanged because the metal (due to heating) penetrates into the fibers of the bronze and fixes it there. This process does not have the disadvantages of gold plating, which quickly becomes opaque and loses all effects.
From an artistic point of view, bronzing allows the copper fittings to remain golden, which is essential for furniture like Louis XV style. Louis XV style furniture often uses different wood and copper fittings. Contrasting colors to enhance its beauty.
Before using copper accessories, some furniture, such as chairs and mirrors, were gilded in whole or in parts. However, with the passage of time, the gold gilded on the wood will lose its luster, become opaque and dull. It has different degrees of resistance to atmospheric corrosion. In addition, slight vibration will cause the bronzing part to peel off, so the owner of the object must repair it. It is precisely because of these factors that have promoted the increase in the frequency of use of copper fittings, and this kind of fittings can also be easily re-gilded. When their bronzing darkens with age, they can be purified by easily restoring their original luster by putting them in an acid bath.
At the same time, one can also find many copper fittings that were hardly gilded in the 18th and 19th centuries. There are many reasons for this. First, too little gold is used for bronzing; second is the wear and tear caused by cleaning (using certain chemicals), and finally, the air has long corroded it.
In the next topic, I will explain the history of the bronzing technique.