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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Blistering when E-coat over nickel plating
Q. We have parts that can be chrome plated or e-coated. When we have a chrome reject the chrome is stripped leaving behind the nickel layer, then e-coat is applied to save the part. We sand the nickel layer prior to e-coat and are seeing blisters on the surface after e-coat. What could be the cause of this, I don't think we have any residual oil left on the part?
- Sidney, Ohio USA
September 6, 2016
A. Microgels, or Impinged microgel inclusions.
I had a big problem with these guys about a year ago. The defect is typically caused by bad concentrate "let downs" or poorly mixed solid adds. Or from a partially dissolved or reacted chemical contaminate added, dragged or transported into the bath. Since it is only happening with your repaired parts It is likely a reaction with something on the surface of your parts. How are you cleaning/activating your nickel before coating? A good start would be to clean or remake your activator and prep/cleansing baths. Try to through a .5-1 micron filter on for a few hours to clean out larger sized particles from your coating bath as well. A combination of all these steps is how I was able to rid our line of them.
Chance Dunstan
Electroplating/Forming/Coating Manager
Placerville, California USA
September 22, 2016
Thanks for the response. We do not have issues with any other parts only the nickel sanded. I agree with your comment that there must be a residue of some type on the part that the cleaners are not removing.
- Sidney, Ohio USA
September 23, 2016
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