Information on Black Nickel Plating

• For formulation and analysis of black nickel plating, please see Thread 44964

A. A black nickel coating is usually accomplished by electro- rather than electroless deposition. The best known bath forms a Zn-Ni deposit that is very thin (1-2 micrometers, if memory serves) and black in color. The protective value of these coatings is minimal, they are mostly used for decorative and functional (solar energy heat exchangers) applications over a protective layer of nickel or nickel-copper.

A. Lowenheim, in 1978, "Electroplating", McGraw Hill ⇦[this on eBay , Amazon, AbeBooks affil links] describes a tin nickel bath, the deposit has interesting properties, he recommends a copper underplate for best corrosion protection, and ASTM Standard B 605 for more info. I don't know how to blacken this deposit. The finishing of that stainless box sounds like the outside would last forever. You would need a Woods nickel strike for good adhesion first thing, and that is going to drag out a lot of HCl which will be difficult to rinse (unless the box has a hole in closed end).

Maybe today, we should think about the new zinc alloys with a black post-treatment instead of tin nickel.They are very popular with the cable connector set. I am sure that several of the Suppliers in our directory can recommend the best one. There have been lots of letters about zinc alloys, maybe a search of our Hotline page would find something.

Ed. note: Readers may want to hear "The Lost Art of Tin-Nickel Plating".

A. There may be data available, but I would need to run a literature search to know. But for the down & dirty answer:

There may be other 'black nickel' platings, but the only one I am familiar with is a post-treatment black plating on top of regular nickel plating. Any such coloration topping obviously does not run through the plating, and its thickness is minimal. It couldn't have much wear resistance -- even if the material itself were a wear-resistant one, which nickel isn't.

This can be contrasted with black chromium plating, where the material has outstanding wear resistance, and the color runs through the thickness of the deposit.

!! Although not an answer to the posted question I must point out that (contrary to one respondent's comments) electroformed nickel has excellent wear and abrasion resistance. It is the preferred material for the protection against erosion of the leading edge of helicopter rotor blades and propeller blades. Every manufacturer of helicopters in North America (except Robinson) uses electroformed nickel exclusively for this purpose as do all of the manufacturers of propellers for commuter aircraft.

Rob Housman
- Santa Ana, California, USA
2001

Thanks Rob. I appreciate your critique, and consequently I have struck through that phrase of my reply. Still, although thousands of different components are built of electroformed nickel, this is not because of the wear resistance of nickel, but because nickel is so readily electroformable, allowing building of parts of complex and incredibly accurate shape relatively inexpensively -- often hollow parts that can't be practically built any other way.

This particular question has to do with black nickel plating, which to my knowledge is just a very thin and non-wear resistant coating on the surface of the nickel plating. I still believe black nickel plating is not a wear resistant finish; but I do appreciate learning about nickel in rotor blades and propellers and its wear & erosion resistance! Thanks.

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

"Nickel Plating"
by Robert Brugger


on AbeBooks or

Amazon (rarely)

(affil links)

A. Black Nickel is an alloy deposition of nickel and zinc. Corrosion resistance is much worse than pure nickel. I don't know if it is better for wear.

A. Black Nickel , I have seen some versions of this, under various trade names.

Send some sample to John Schneider Assoc. [Mequon, Wisconsin], they have an excellent black nickel process.

A. I understand there might be another "down & dirty" way to convincing Gregory S's colleague -- try to do the strip-off process for the plating of Black-nickel and other nickel treatment process (for example, Electroless Nickel, Bright Nickel, ...) Compare the process -- you will find which plating is more corrosion resistant.
And to do it in a very formal way, do some salt spray testing.

"Nickel Plating Handbook 2023"
by The Nickel Institute

View On-line for Free

A. Sorry, Marisa, but I don't fully understand your question. If these hammer marks are undesirable scars, no, plating will not fix them -- only sanding and polishing can remove them.

If you are talking, however, about a decorative effect, the plating will not significantly obscure surface texture. However, black nickel and most plating, being opaque, will obscure reflective highlights.

A. from PFOnline:

Black nickel plating is lustrous and has a black or dark gray color. Plating is done with little or no agitation. Occasionally it is necessary to remove hydrogen gas (bubbles) from the part's surface using wetting agents. The pH of the bath ranges from 5-6, and the temperature varies from ambient to 140 °F. Current density remains at approximately 0.5 A/dm2.

The coatings average 2 mm thick and corrosion resistance is limited, therefore they are usually lacquered or coated with oil or grease. If the black nickel must have good corrosion resistance, an undercoating such as bright or dull nickel, zinc or cadmium is necessary.

A. Sorry, cousin, questions of the style "What undesirable effects can result from doing it wrong?" are similar to what will happen if I run a Stop sign; but assuming that this is the zinc-nickel alloy plating, its composition will probably even be wrong -- it won't even be black nickel plating anymore. Good luck.

Regards,

A. Hi Janet. Between the link you provided and the information already on this page, what occurs to me is that the nickel plating on your faucet was not thick enough -- with the consequence that the underlying steel discolored and rusted.

There are interpretation issues, however. First off, "tarnish" may not mean quite the same thing to you and to me and to other readers. Secondly, we're assuming that the finish on the faucet was in fact black nickel plating when it may not actually have been despite any labels (sellers may use words in the most appealing way, and may sell you a black nickel "look" without necessarily having done the "black nickel plating process" described on this page). Thanks for the info!

Regards,

A. Black nickel is a very thin plate and is prone to scratching if abused.
When you say vacuum, is that a soft or hard vacuum and at what temp.
I would think that it would work since it is an alloy and not a solution of metals. Try a scrap piece to have a better idea.
Black chrome would be more durable and should not be bothered by a vacuum at a reasonable temp. It does cost a lot more.
Not many shops do either of these coatings.

Q. As follow-up, the black nickel application is a hard vacuum (i.e., outer space) and the worst-case predicted temperatures are approximately 400 °C.
Since I couldn't find any data for black nickel at these temperatures, I am conducting a thermal vacuum compatibility test.

A. Sorry I am late to the party--black nickel plating.

As a silver smith and metal artist I have explored and used bright nickel and black nickel plating on 101 copper and 260 brass.

The bright nickel at 125 °F with moderate agitation and .07 amps psi(per square inch) at 30-45 min duration plates excellent and has very good flexibility--260 brass plates the best with no hot spots or spotty coverage.

The black nickel however always has a hot spot and the plating can in some instances just rub off---not good for jewelry. Having tried 7 different temp/elect/cleaning/time sequences has led to several pieces that have not released the black nickel.
Whatever plate you choose just make cleaning a super high priority.

A. Hi Martin. We appended your inquiry to a thread on the subject where Cameron and James seem to advise that you should probably lacquer it for good life.

Regular bright nickel would not usually be clear coated because the tarnish is not considered unattractive, but black nickel is apparently more subject to corrosion and tarnishing. Brass plating is clear coated not because of its softness but primarily because of its tendency to very bad tarnishing.

Regards,

A. Hi Martin,
I agree with Ted, Ni plating can become scratched fairly easily and can be discolored especially if it sees a lot of moisture assuming you are referring to Ni sulf. If you mean Ni phos, it may not get scratched too much and discoloration is not usually an issue except for an occasional yellowing but a clear protective coat/lacquer helps avoid scratches and discoloration.

A. Hi Elie. I think I would look into a tinted matte lacquer or clearcoat to try to soften the shine of the black nickel (but your question is vague to me, and guessing whether a finish will "wear off" a "brass product" which could be a thousand different things used in a thousand different situations is obviously difficult).

"Black oxide" could mean something different to a jeweler than to a gunsmith, but if you are referring to the high temperature caustic bath used on gun barrels, it won't work on nickel or chrome plating; if you are referring to some sort of sulfide-based process for cold blackening of copper and brass, I'd agree that its wear resistance is probably low. Good luck.

Regards,

A. Hi cousin Justin. It looks to me like the knobs were black lacquered or clearcoated after the black nickel plating ... but we can't resolve problems with guesses :-)
If lacquering was "demanded" you must have certifications from your vendor that the parts were in fact lacquered.

From this distance it looks to me like there was poor adhesion of the black nickel and subsequent lacquer to the underlying nickel plating. Do you sometimes buy these knobs in a bright nickel finish? The reason I ask is that blackening must be done immediately (before the bright nickel becomes passive), and a possibility here might be that knobs with bright nickel plating that had become passive were put into a black nickel process and which therefore adhered poorly.

I know from your e-mail address who your company is and what this product is ... but you used a fictitious name, did not supply your city name, and have not told us the application -- so I'm just not sure how much I'm supposed to explain to other readers so they can help you vs. what I've figured out but should be kept confidential :-(
For the readers/responders to not know what this is actually about, and what cause their efforts are contributing to is unsatisfactory for this public forum -- so spill the beans or this response was one-and-done :-)

Luck & Regards!

A. What black nickel process has been tried?
I've used black nickel sulphate and black nickel chloride; nickel sulphate looks similar to your pic; the chloride is darker black, but is extremely soft, so not a good fit for your application.
You could blacken a low-phos electroless deposit. Powder paint would give the best wear characteristic.

A. Hi Vasanth,

You may consider plate black ruthenium on nickel deposit.

Regards,
David