Fire gilding: A perilous process for gold-plating in which an amalgam of mercury and gold is applied to an object and then exposed to heat to vaporize the mercury and leave the gold behind in a thin layer. Fire gilding also is applicable to plating silver, copper, and copper alloys. The process of fie gilding is still used when antique work is to be repaired or an exact replica made. Fire gilding is hazardous because mercury vapors are emitted even at room temperature, presenting an appreciable risk of mercury poisoning. Fire gilding is also called mercury gilding.