Recent developments of electroforming with precious metals for jewellery

In comparison to conventional techniques, electroforming as a manufacturing process for gold and platinum jewellery provides enhanced design potential as well as savings in metal costs. With the use of suitable gold electroplating baths which ensure deposition within a narrow caratage range the viability of hollow gold jewellery manufactured in this way that can be hallmarked is guaranteed. For this reason electroforming is an ideal process for manufacturing large articles of gold jewellery with an interesting design which will appeal to today's jewellery customer. With the development of electroplating baths for the deposition of 8, 9, 14 or 18 ct gold-silver alloy coatings toxic heavy metals such as cadmium, which have often been used in the form of gold-copper-cadmium coatings, can be excluded from the production of gold jewellery using electroforming. The gold-silver baths operate at a temperature of approximately 40 degrees C. Thus the wax injection technique used in conventional gold jewellery manufacture to produce wax cores can be applied without modification. The wax core technique is superior to all other processes that use metal cores or base metal intermediate layers. Recent developments resulted also in a 24 ct-process to deposit pure gold especially for jewellery and decorative articles for markets in the Middle and in the Far East. Due to the low bath temperature of 45 degrees C the wax injection technique cart be applied, too. With regard to electroforming with platinum preliminary results of recent research work are presented The electrolyte is acidic and leads to bright deposits as plated. As the electrolyte works at 75 degrees C an intermediate auxiliary layer of silver on the basic wax core has to be used. In addition, electroforming with silver from an adequate electrolyte is described briefly.