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Do I need copper plating (cyanide and acid) under nickel chrome plating?

Is it necessary to apply copper to cold rolled steel prior to nickel/chrome plating? It is an automotive product where we have had corrosion problems. Product requires chrome decorative plating for looks. Thank you.

Bob Austin
Manufacturer - Fort Worth, Texas
November 2, 2010

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Hi, Bob.

Copper plating under nickel-chrome has a few roles today. First it is used on plastic parts to improve their thermal cycling ability; second, enthusiasts feel that the best, more mirror-like, "show chrome" requires buffed copper underneath; third, it may be necessary for plating zinc or aluminum parts because you can't directly nickel plate them.

It is not usual to copper plate cold rolled steel anymore, rather, it is usually directly nickel plated, and I don't think there will be corrosion resistance problems due to this. The most important key to corrosion resistance will probably be duplex nickel plating, i.e., depositing semi-bright nickel first, then bright nickel. With this approach, this bright nickel plating will sacrificially protect the semi-bright nickel plating, spreading corrosion potential laterallly instead of into the steel in the event of a pit or porosity. Google ' "Step test" nickel'. Good luck.

Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
November 3, 2010

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Bob,
1. It depends on your cosmetic requirement of 'decorative plating'.
2. With steel substrate, you can plate directly with bright watts nickel followed by chromium plating.
3. For a far superior 'mirror like ' finish, cyanide copper strike, followed by acid copper, buffing then nickel chrome plating is the norm.
4. Since you have corrosion issues, the duplex nickel as Ted suggests is the way to go.

SK Cheah
- Penang, Malaysia
November 9, 2010