4. Modern processes

4.1 Liquid gold from organometallic compounds

This is the name given to a process that first appeared in the middle of the 19th century, based on the surface application of a resin composed of organic products containing gold, followed by firing at temperatures of around 600°C to decompose these products and leave a layer of gold that is generally very thin (0.2 μm). The process, which is easily industrialized, is widely applied to glass and ceramics, in particular for tableware, but also to a variety of other substrates.

The products making up resins are now generally organic compounds, prepared from gold halides and natural sulfur-containing terpenes and/or balsams, soluble in essential oils. Initially, more stable and soluble terpene gold mercaptides replaced...