Metal finishing Q&As since 1989

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Nickel Plating Problem (ph)

On occasion the pH of our Bright Nickel Bath drops to 2.0. Our desired ph is 3.8 to 4.2. What is the best and quickest way to get the pH back up without damaging the brightness of the finish? The bath is 2000 gallons and the temp is 140 degrees. Thanks

Mike Capps
Lab Tech-Electroplating Business - Bon Aqua, Tennessee, USA
2006

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I find it hard to believe that the pH drops to 2.0 by itself with no additions having been made and with nothing radically wrong, because the natural tendency is for the pH to rise during operation. So I think that bears investigation to avoid getting into a battle of contrasting additions as in "Chemical Balance". We have several letters on line here about raising the pH of a nickel bath; put 'nickel carbonate sodium hydroxide' into the search engine.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2006

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First of three simultaneous responses --

If your pH is dropping, your anodes have passivated or you have something acting like an insoluble anode. Or you have a serious drag in problem.

James Watts
- Navarre, Florida
2006

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Second of three simultaneous responses --

In addition to knowing how to raise the pH of the nickel solution, you should be very concerned with why it got that low. Some common reasons would be high drag in of acid pickle (especially when doing parts with blind holes or cups).

Gene Packman
process supplier - Great Neck, New York
2006

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Third of three simultaneous responses --

I am surprised the pH falls to as low as 2. I could perhaps imagine it happening near the anode whilst the bath is being used but not agitated, but as soon as the current is turned off, it should go back to a more sensible value. Alternatively, perhaps your boric acid is out of spec. You give no analyses, so it can only be a guess. I would suggest the source of the problem is found before you start to find rapid fixes.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2006