Q. Our cyanide copper strike bath builds up copper metal over a period of time. Why is this happening?—B.R.
A. I receive this question often, but the answer is always worth repeating. You are not creating matter. This type of bath is operated at low cathode efficiency, generally in the range of 50-60 percent. This allows for better coverage, cleaning and activation of the parts. To achieve this type of efficiency, the bath will contain a lot of free cyanide, and this high concentration of free cyanide enables the copper anodes to remain unpolarized. The anodes will continually dissolve and the copper concentration in the strike bath will increase. You can minimize this by removing the anodes when the bath is not being used.