A gold gilding technique in which an amalgam of gold with mercury is applied to a metal, such as copper or silver, then the metal is heated to flash volatilize the mercury and deposit a thin layer of gold. Fire gilding has been used since at least 300 CE in China. In most regions, it was replaced in the mid-19th century by electrogilding.
P.T.Craddock, "Gilding", The Dictionary of Art Grove's Dictionaries, New York, 1996.