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White crystals in copper plating tank

White crystals form at the bottom of our copper preplate tank. Do you have any suggestions to correct problem?

Bob Ross
Shop employee - New York, USA
2007

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First of three simultaneous responses --

"Pre-plate tank?" You mean, a cyanide copper strike?

Sounds like sodium carbonate / washing soda [affil links], esp. if you're seeing them in conjunction with the low temperatures we've been having around here lately. You could see if the crystals dissolve in plain DI water; and, if so, if the solution turns milky on the addition of calcium chloride solution, or lime water.

If it is carbonate, just remove the solids. Best idea: REALLY chill the tank by adding some bags of ice, or with some kind of chiller unit, and get as much out as possible. If your carbonates are that high you are not far from some kind of problem.

Dave Wichern
Consultant - The Bronx, New York
2007

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Second of three simultaneous responses --

What is your process and what is the bath composition supposed to be?

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2007

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Third of three simultaneous responses --

The white crystals at the bottom of your copper tank could be several things. They could be undissolved salts, carbonates, a product of a reaction with drag in, etc. Please describe what the pre plate is: a plate or a strike. I am presuming it is a cyanide bath. State what the chemical compostition is (or should be) and your operating temperature. Is it a barrel or rack tank. Are you using any agitation.

It really is necessary to have some facts to try to give an answer that has any validity.

Gene Packman
process supplier - Great Neck, New York
2007