Metal finishing Q&As since 1989

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Yellow nickel plating

I am interested to learn about yellow nickel plating process. Thanks in advance who is able to let me know.

Redzep Musovic
ing. chemistry - Nis, Serbia, Serbia and Montenegro
2004

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Nickel tends to be slightly 'yellowish' in color compared to metals like silver or chrome, Professor. It can get somewhat more yellowish as it tarnishes over time. But this effect is faint, the nickel is still basically white and reflective, would never be confused with brass or gold, and a layman would not call it yellow. Sorry, I've never heard of a 'yellow nickel plating process'.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

I got some samples from Sweden, for the door-window, for thermo furnace that have plate nickel, and other plate over it which is yellow, the same as the brass or gold. The plate is not surfaced with lacquer. The yellow surface conducts electricity and it is constant colour. What do you think about it? What is the process? Thank you.

Redzep Musovic
ing. chemistry - Nis, Serbia, Serbia and Montenegro
2004

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2004

Well, nickel is not the color of gold or brass. I am not particularly knowledgeable of atomic physics, but I do understand that the color of metals is related to their electron energy levels, and that gold and copper are their special colors because of that.

So, in my estimation, there is either something on top of the nickel (zirconium nitride or titanium nitride PVD finish, perhaps?) or it is not nickel plating, but some kind of alloy. Is it possible to apply a spectrometer to get some elemental analysis?

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

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"The finish that will work well for you is Alkaline Zn/Ni 12-16% Ni. This process with a yellow chromate will give at least 1000 hours NSS to white rust and 2500 hours to red rust (assuming 8 microns minimum). The product produces very little in the way of white corrosion products and has excellent slip properties."

It is yellow, it has excellent slip properties. But I can't confirm or deny that it has any relation at all to the "yellow nickel" process. Maybe the phosphorus content affects the color too...

As nickel plating can be done in pure black - the metal to be actually black, not blackened afterwards, it seems reasonable to believe that similar can be done to make it yellow. Perharps The carbonate-based NiP plating can be used to trap some oxygen or nitrogen impurities, perharps the zinc mentioned earlier, but this all is a wild, wild guess.

I found something vaguely related "FMC C81005: Coating (Polyimide Resin, Yellow Teflon) "... there is so many yellow coatings

Mario Romaior
- Skalica, Slovakia
August 14, 2010

This is actually interesting, because a friend reported that cylinder liner block ordered to be "nikasil plated" in italy, arrived in yellowish colour. I can not confirm if the yellow is gold, molybdenum or 2 micrometer thick nitride coating of any sorts, but the result is that the coating has very low friction coefficient and exhibits better anti stick and anti wear properties than comparable process produced elsewhere.

The main difference is the yellow colour.

In other place Jonathan Timms - Hong Kong mentions this: