I've seen coin art that has gold applyed to different areas of the coin. How is the gold applyed? Is some place that explains the process/materials used?
Hi jgandolph, and to the forum. One method, which is used for putting gold trim on china, glass, picture frames, etc., is to apply a substance called "gesso" to the area where gilding is desired. Gesso is a self-leveling paste that can be thinned down and applied with an artist's brush. Gold is an extremely malleable substance, and can be made into very thin sheets, called "gold leaf". Gold leaf is applied to the gessoed area, and "burnished" so that it sticks only where wanted. The burnishing is done by rubbing the area with a small smooth tool until it adheres. Then the loose flecks of gold that had no gesso to stick to are brushed off, usually with a camels hair brush, and the result is a gold-colored area. If you want to try it yourself, most craft shops sell small packets of gold leaf, gesso and burnishing tools. The gold is so thin that it is virtually weightless, and the sheets are quite inexpensive. (If you do try it, come back and tell us how it went. ) To find out whether any particular private mint uses this method, or a different one, to "decorate" coins, you would have to ask them.
They also use electrolysis (SP?). they take the item to be plated and put a positive electrical charge on it. They then submerge the item in a electrolyte and place a gold ingot in with a negative charge. The molecules of gold migrate to the plated item and are deposited on it. This is a simplified description but it covers the basics.
That works fine for gold plating the entire coin, but jgandolph was specifically asking about the ones with a gold "spot" on a silver coin. To deposit gold on a selected spot would involve a careful application of a "resist", such as wax, laquer, or something similar, to everyplace that isn't supposed to be platied. Then the resist material on the coin would have to be (forgive the "dirty" language) cleaned off. I can tell you from experience with making printed circuit boards that electroplating selected areas is a lot more labor intensive than simply applying gesso and burnishing gold leaf to those areas.
Alternatively you can do gold plating. The idea is that you melt the gold in an acid which becomes a gold solution. This can be applied on any surface, providing that the acid isn't going to burn the material that you are going to apply on. I am not too sure after the process after that but if I remember right, it is applied with some chemical treatment after that. What exactly the chemicals are, I am not too sure. This is done pretty extensive, especialy on gold platings in ceramics you see.
None of the techniques described would seem to be practical for mass production.How does the Canadian Mint make 25-50 thousand of these.Is there a way of applying the gold layers onto intricate pattern details by machine?I've also been wondering since I started collecting the flower series 4 years ago.
"selective gold plating" as the royal canadian mint calls it, a patented process in their advanced technology department, by which gold can be deposited to exacting specifications relatively fast, by my understanding the gold is one of the operations to the coins, the details of such operation would take hours to explain but only minutes to preform. by the way nice proof coins.
satootoko, Here's all I could find on the subject,click on the selective plating link: http://www.brushplate.com/brushplate.htm
