À la mercure is a French term to describe fire gilding through the use of a mercury/gold amalgam. The pure gold forms an amalgam with the mercury and is "painted" on an object, after which the item is fired with an open flame or in a furnace, vaporizing the mercury and leaving behind a layer of pure gold. This highly toxic method of gilding has gone out of use and is only applied when an item is in need of restoration. Often a special permit is required to execute this type of gilding.
Alternative names: mercury gilding, fire gilding.