Metal finishing Q&As since 1989

-----

Gold passivated zinc vs. galvanizing vs. chemical nickel

Designer wants chemical nickel on mild steel instead of using stainless steel. Plater says GPZ [gold passivated zinc plating] is better than galvanising (use is fresh water) Does anyone have advice?

John Moorfield
project manager - Exeter, Tasmania, Australia
2006

---

Galvanizing means hot-dipping in zinc, and nickel is not interchangeable with zinc. If you need nickel plating you need to electroplate or apply electroless nickel plating; you won't get a nickel coating from galvanizing, John.

Galvanizing is much thicker than electroplated zinc, and therefore more corrosion resistant; so it's hard to claim that GPZ is better than galvanizing unless you are referring to appearance or the need for close tolerances. Please submit a followup and we'll try to help.

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

---

2006

John

You are limited by the eventual corrosion protection the finish is expected to accord the component..

But you have not stated what is the component and what is the life expectancy of the finish. So the following replies are equally vague.

These choices are subject to corrosion resistance demanded ..and are listed in order of protection accorded.

1) SS duly passivated .
2) Nickel , possibly Chemical ? Duplex Nickel electroplated and followed by Chrome.
3) Zinc Alloy plated with TRIVALENT Thick film Passivate followed by a topcoat.
4) Hot Dip galvanised finish as a LAST resort.

I hope this helps.
Regards,

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016