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"Can I dilute my copper plating solution?"
July 23, 2016
Q. Hello! I have been copper plating (not forming) for a while now and everything is going great! I have noticed that my solution seems to be lessening in my plating jar over time. My question is, can I add distilled water to dilute it and bring the solution back up to the desired level? I'm not assuming that my solution needs to be up to a certain level in the jar but I want to double check with you guys. Follow up questions: Why/how does the solution evaporate in the first place, and will it contaminate the air in my work space?
Designer - Portland Oregon USA
A. Hi Stephanie. There is some measure of complexity to plating solutions. They contain copper, various copper salts, acids to maintain a particular pH, and often addition agents like wetters and brighteners.
Industrial platers would use the same tank of copper plating solution for years or decades -- doing the necessary chemical analyses then making the necessary additions to keep it in balance. In your case the volume of plating solution on hand is so low that the cost of the necessary analyses would probably be greater than the cost of replacing the jar of plating solution. This leaves you in the position of being restricted to guessing what would need to be done to the plating solution to keep it in balance. My guess is that it will be closer to remaining in balance if left alone than if diluted with distilled water, but if you tell us more about it, including what temperature you electroplate at, a better guess might be possible.
The plating solution should come with a Material Safety Data Sheet that advises you of the principal chemicals in the solution and the hazards involved with them. When no electricity is applied, the principal thing evaporating is just water, although some acids like muriatic acid can 'evaporate' into your work space. When you are plating, hydrogen and or oxygen bubbles form on the parts and the anodes and as these detach and reach the surface they can convey some plating solution into the atmosphere in the same fashion as ginger ale and champagne. It's probably not a big deal, but it's very hard to say that it is nothing to be concerned about without knowing a little more though.
Ted Mooney, P.E. RET
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