Mercury gilding (amalgam gilding or fire gilding) is an ancient technique, and it is apparently attested in the West from around the mid first millennium BC. We must note, however, that only very few gilt objects have been properly analysed and that, until now, the problem of the origin of mercury gilding is generally very little researched in different parts of the world. The earliest examples of amalgam gilding in Asia seem to come from China and are dated to the Chan Kuo or Warring States period (475–221 BC). It is unknown exactly when the earliest amalgam gilt objects appear in Japan. This technique, however, seems to have been used surely since the Nara period (710–794 AD), and it was widely employed in the Edo period.
In recent times, this technique has disappeared from all decorative metal workshops, with very few exceptions, because of the high toxicity of mercury. A notable exception is the Morimoto Kazari Kanagu Seisakujo in Kyoto, a specialized workshop that is very active in the restoration and reproduction of decorative metal details in the field of Cultural Heritage. The workshop has operated since 1877 (Meiji period) by using ancient techniques, including amalgam gilding, to produce architectural metal fittings, metal decorations of shrines and ceremonial utensils. In this paper, the beginnings of the technique will be briefly outlined, and the procedures employed in the Morimoto workshop for the production of traditional decorative metalwork will be described and discussed.