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Nickel vs. zinc plating as undercoat for stoving paint or powder coating?

April 13, 2011

We produce an infant silicone teether with a metal clip that attaches to a childs upper garment.
Currently we are using stoving paint due to its color matching abilities to pantone codes. Powder coating is an option but have to buy bulk for custom colors and create hanging holes in the clip.

Currently the clip has nickel plating and am basically
trying to determine whether to switch from nickel plating to zinc plating for better adhesion, as we have had issues with paint adhesion.

1. Does the nickel help in preventing rust? Which one is better?
2. With zinc plating, will the primer and paint adhere better?
3. Which one is more toxic, zinc or nickel plating?

Our products are CPSIA tested and approved (low lead content etc)

Appreciate any answers.

Damian

DAMIAN BARTON
PRODUCT DESIGNER - MIAMI, FLORIDA USA

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Hi, Damian.

Either may be overkill, and a zinc phosphatization pretreatment is probably about as good for corrosion resistance, while designed for the purpose of pretreatment before painting or powdercoating. Neither type of plating is without issues for paint adhesion, but zinc plating is probably somewhat better for corrosion resistance and adhesion than nickel plating, as well as less costly.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 13, 2011

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April 14, 2011

Ted,
would you say that zinc plating is less toxic than nickel plating....generally speaking.

Thanks again.

Damian

Damian Barton
- Miami, Florida, USA

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Hi, Damian. Here in New Jersey a previous governor made clear that: "'Toxic' is a matter of statute, not opinion", which means, I guess, that you'll need to find and study the statutes on the subject :-)

But who can really say anyway. Neither is designed to be eaten; many people are allergic to skin contact with nickel, but the chromates used on zinc are probably as bad or worse, and zinc is not meant for skin contact. I just opened a box of zinc galvanized washers, which came with 5 labels that the "product contains chemicals known to the State of California to cause cancer, and birth defects or other reproductive harm". The State of California hasn't said which chemicals, so the label could be based on a trace amount of nickel in the galvanizing rather than the chromate for all we know.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 14, 2011

Have you considered changing the clip for plastic? That way, only the spring would be metallic. G. Marrufo-Mexico

Guillermo Marrufo
Monterrey, NL, Mexico
April 19, 2011