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NICKEL ACTIVATION PRIOR TO CHROME

I was wondering if some kind folks could shine some light on a question/problem I have. It has to do with nickel activation. The parts have been nickel plated in a standard watts bath with brighteners/levelers. If needed then they are buffed to a perfect finish. Some of the parts have been plated for about 3 months now. My question is about activating the nickel. I have cleaned/degreased and immersed in the sulfuric acid bath and it seems the water still beads up and runs off the surface. I have cleaned/degreased and immersed in my proprietary METAL ACTIVATOR and still the same results. With highly polished nickel with this be the normal results? Or will the water sheet on the part as with a clean copper plate? The only way I can seem to get the nickel to hold the water on the surface is to electroclean in the METAL ACTIVATOR or acid bath. But, then the plating is dull or darkened. The next step is chrome plating but I'm afraid it will not look to nice if I use the part that is darkened.

Thanks for your help,

Tom Haltmeyer
- Peoria, Arizona, USA
2002

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As a bare minimum you must go through alkaline cleaning, acid dipping, and Wood's Nickel Strike. You may still have problems, but that's the minimum.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002

You need to electroclean cathodically in an alkaline electrocleaner that is formulated for use with nickel then activate with your proprietary activator. That should do it.

Russell Richter
- Danbury, Connecticut, USA
2002

We used to experience this problem in the "good old days" when replating bumper bars. We used to treat the nickel plated item anodically in a propriety cleaner sold by the now defunct Cannings called "Kleenwell". This was a cyanide cleaner.

Raymond Sebba
- Cape Town, South Africa
2002

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First of two simultaneous responses --

You should not have to buff your nickel if it has been freshly plated. Problem with the nickel bath? See your vendor. If you are buffing, you need a good soak cleaner to remove the compound before the nickel cleaner/activation step, then acid salts (proprietary).

Bill Hemp
tech svc. w/ chemical supplier - Grand Rapids, Michigan
2002

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Second of two simultaneous responses --

You don't mention whether your activator is acid or alkaline. Usual practice is to use cathodic activation with both acid and alkaline processes. Nickel will become passive with any oxidative situation (even induced via bipolar effect) so anodic is out. If anodic cleaning is used it must be followed by cathodic alkaline or acid process to remove the oxide film. While anodic acid may activate it will also tend to dissolve and therefore may dull surface. If you are getting darkening in cathodic situation then replace process as it is contaminated or unsuitable. My preferred process would be Cathodic in cyanide containing alkaline cleaner e.g., 30g/l Sod cyanide 20g/l Caustic soda followed by Cathodic in 10% sulfuric acid.

Geoffrey Whitelaw
- Port Melbourne, Australia
2002