Understanding the fate of tin in cyanide-free bronze electrodeposition baths
The Loony is a symbol, recognized by all Canadians. While it looks golden, the Royal Canadian Mint is producing its yellow color with an alloy coating on the coin surface. Yellow bronze is a hard and esthetically pleasing material that can be used as a coating for such coins. Internationally, yellow bronze coatings are predominantly produced from cyanide-based electroplating baths. This comes with significant risks to workers and the environment, regulatory restrictions and costs for waste treatment. The Royal Canadian Mint is currently developing a yellow bronze plating bath that is free of cyanide, to be used for yellow metal coatings on Canadian and international circulation coins. This project serves to understanding better how tin binds to other chemicals in these solutions and how to make tin more available for electrodeposition. In doing so, it contributes to the development of cheaper and environmentally friendly coin production technology.