Louis XV Ormulu Andirons

One of the most valuable secrets of French metalworkers in the 18th and early 19th century was the gilding of brass and bronze, called ormolu. Fine gold powder was mixed with mercury and then blown onto the object to be gilded or it was applied with a brush. Then the object was heated with fire, causing the mercury to evaporate and depositing the gold onto the bronze. The technique was very dangerous because of the released mercury vapors. Around 1830 this technique was officially banned because of the health risk for the craftsmen. After that electroplating gradually took over, which was less refined but more economical and less dangerous.