Also called 'fire gilding' or 'amalgam gilding'. A process of applying gilt to metals used from the seventeenth century onwards and later used for ceramics as well. It is still used occasionally. An amalgam of gold and mercury is applied to the object that is then fired in a low-temperature oven so that the mercury is driven off, leaving a thin film of gold. The process is usually repeated several times until the layer of gold is thick enough to be burnished to a hard brilliance. A variation of the process, known as 'matt gilding', was invented towards the end of the eighteenth century, probably by Gouthiere. The process can only be practised under severely restricted conditions today because of the harmful effects on the craftsmen. The mercurous oxide fumes driven off in the process are highly noxious and, in the eighteenth century, very many workers and craftsmen perished from 'phossy jaw', a disease caused by mercury gilding.