Liquid Gold

Also known as liquid bright gold, is widely used in the decoration of ceramics and glass, particularly perfume bottles, and also has special applications in aerospace and electronics. Liquid gold was first manufactured by the technical manager of the Royal Porcelain Factory at Meissen in Saxony in the early 1830s but the formula for mixing gold powder in suspension with natural oils and chemicals was kept secret until 1851 when a patent was taken out.

Degussa, the German precious metals group, started liquid gold production in 1879 and shortly afterwards shared its knowledge with Johnson Matthey in Britain. From 1905 Engelhard Industries, Hanovia liquid gold division, became the main supplier for the American market. These three companies have always dominated production, which requires about ten tonnes of fine gold annually.

A bright film of 22 carat gold adorns
a Limoges plate (Credit: World
Gold Council)

A typical liquid gold solution may contain between four and twelve per cent gold dissolved from granules with as many as forty ingredients including natural oils from lavender and balsams, natural resins and organic acids. In addition, the solution contains minor amounts of other metals such as rhodium and indium to promote a fine grain for a uniform bright film and adhesion to the substrate. Hundreds of formulae exist, depending on the precise needs of the decorator.

The liquid gold may be applied to ceramics and glass by manually brushing, screen printing or spraying. The object is then heated in air to burn off the organic components, leaving behind a thin ‘bright’ film of 22 carat gold. While used primarily in the ceramics and glass industries, liquid gold is also applied to glazing tiles or bricks for the outside of buildings. The most notable was the Richfield building in Los Angeles, which had a ceramic veneer finished with liquid gold. Where a rich, matte gold is desired, a burnish gold formulation is used. This contains gold flake and/or powder in addition and fires to a dull matte film which is then hand burnished to the final rich gold appearance. Gold’s efficiency as a reflector of heat and infra-red radiation has led to liquid gold being used to reduce heat transmissions from aircraft engines and in the United States’ Apollo space program. In the latter, reflective gold-coated plastic film was wrapped around parts of the lunar landing module and the moon buggy to protect sensitive parts from solar radiation.