Gold and its alloys have been used for decorative purposes for more than 6,000 years.
Major Gold Products Used in the Decorative Industry
As with the other applications this use is attributable to the unique combination of properties gold offers: its unique appearance, colour and beauty, the ease with which it can be fabricated and its corrosion resistance. To provide a suitable in-service durability, gold coatings should have a thickness of at least 10 microns, although for indoor decorative purposes layers of less than 1 micron with a subsequent lacquer application may be appropriate. The four important gold products used in the decorative industry are:
Gold salts for decorative plating purposes are often based on gold cyanide or sulphide. They are used in the form of aqueous solutions or as crystalline salts, for the decorative plating of innumerable gold coloured articles in everyday use. BJS has invested in the installation of super size electroplating tanks in its manufacturing facility - each with a 10 cubic metre capacity - to electroplate gold onto very large stainless steel items and they are seeing a growing market for this service in the yachting, architectural and aircraft markets. Interested industrial designers should contact the company to explore the design opportunities.
Rolled gold is used in the manufacture of products clad with gold such as high class jewellery, pens, lighters etc. The material has a sandwich structure comprised of a base of copper or nickel alloy topped by one or more gold alloy layers. The adhesion of the individual layers is achieved by pressure and heat, and the subsequent material is rolled in a mill.
Liquid gold is also known as bright gold and is widely used in the decoration of ceramics and glass, particularly perfume bottles.
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, Hanova liquid gold division, became the main supplier for the American market. These three companies have always dominated production, which consumes about ten tonnes of gold annually.
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 to promote a fine grain for a uniform bright finish and adhesion to the substrate. Many different formulae exist, depending on the precise needs of the end user.
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.
Alternatively a rich, matt gold finish may be required and in this case a burnish gold formulation is used. This contains gold flake and/or powder and is fired to a dull matt film which is then hand burnished to the final rich gold appearance.
Visually the most spectacular use of gold in a decorative application is gold leaf. Gold leaf is generally produced by hand beating (thicknesses of only 0.1 microns are possible) and is widely used as a decorative layer by builders, glass makers, printers and artists.
Gold leaf is often used to highlight the gates and fences of important buildings. For outdoor applications several layers are generally used to provide excellent protection against corrosion. Gold leaf may be supplied in books of individual leafs or in rolls of up to 20m. Pure gold leaf, if folded, can weld itself together and it is therefore generally used for the thicker grades of gold leaf. The thinner leaves are usually an alloy gold, silver and copper.
Source: World Gold Council
For more information on this source please visit World Gold Council