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topic 51932

Want Dark or Black Electroless Nickel Plating

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A discussion started in 2001 & continuing through 2017


Q. I'm a job shop plater, and looking for a way to blacken electroless nickel. I've tried and seem to get a black rainbow film look. I need a uniform black appearance. Can anyone help me? I also would like to know if there is a such thing as black electroless nickel. Any help would be appreciated.


Lee, Min-Gu
- Inchon, Korea


A. Another plating shop near us do a nickel PTFE coat that is black. You could try this for a black ENP.

Martin Trigg-Hogarth
Martin Trigg-Hogarth
surface treatment shop - Stroud, Glos, England

To minimize searching and offer multiple viewpoints, we've combined multiple threads into the dialog you're viewing. Please forgive any resultant repetition or failures of chronological order.

April 21, 2009

Q. Greetings all,

Having worked hard to maintain bright EN coatings, I have been asked if I can darken one up. We plate parts for military applications. Our spec calls for a nickel plated part (both corrosion resistance and electrical conductivity are important), and some of our more aesthetically sensitive team members would like it to be dark to better match the rest of the final assembly. Is there a way to make the coating a nice charcoal gray without compromising other coating properties?

Thanks in advance for any direction.

Michael Costello
Plating Engineer - Grand Junction, Colorado

April 23, 2009

A. By darker, I assume that you are talking about gray to light black. You will not get that from an EN tank. You need a black nickel tank which is quite picky and moderately difficult to get repeatable color. It basically is a zinc poisoned nickel bath. Note that there is a zinc- Nickel bath that is much easier to operate, but colors tend to wander a bit more.

If all you are looking for is a light matte gray, keep an EN solution that you are going to dump and dissolve aluminum in it. It will get a light matte gray. It will be slower.

James Watts
- Navarre, Florida

April 27, 2009

Q. James,

Thanks for the aluminum direction. How much is necessary to get the gray matte? How much longer would you expect on the plating time (i.e. we run a load for around 40 minutes right now. Will I need 50, 75 with Al in the solution?

Much appreciation.

Michael Costello [returning]
- Grand Junction, Colorado, USA

simultaneous April 28, 2009

A. I really do not know how much Al. when we had a tank that plated virtually nothing but aluminum, it would gradually become gray.
A foggy remembrance is a 10 - 20 % longer time. Of course, temp and pH are major players in time.

James Watts
- Navarre, Florida

April 28, 2009

A. To achieve grey to black using electroless nickel, Use a EN solution that uses thiourea as a stabilizer (bright EN) After plating, immerse the plated item into 30-50% nitric acid for a short time. The longer in the nitric acid the darker. this dipping is done for 20-40 second. Longer time will dissolve the electroless nickel deposit. Plate a relatively thick deposit of EN, 0.0006 to 1 mil depending on the corrosion protection needed.

don baudrand
Don Baudrand
Consultant - Poulsbo, Washington

(Don is co-author of the
book "Plating on Plastics")

April 28, 2009

A. Michael

Google search "super black coating". You may be able to find adequate information to achieve the desired results. I thought the etchant was nitric acid.

Willie Alexander
- Colorado Springs Colorado

Moisture exuding from black electroless nickel plating during bake

November 30, 2017

Q. My company is manufacturing a part that requires us to black electroless nickel plate 6061-T6 aluminum per SAE AMS2404 [link by ed. to spec at TechStreet], class 4, grade B, and then powder coat. We have been experiencing an issue where the cured powder coat will adhere to surfaces it comes in contact with during a bake cycle for a later process, and peel off our parts. Trying to determine the cause we baked the plated parts upon receiving them from our vendor and noticed that multiple parts exuded some moisture through the nickel plating and believe this is what is causing our powder coat issue. I have tried researching what could be causing this and have not been able to find any information. I was hoping someone could shed some light on what is causing the moisture and how to prevent it. Thank you!

Daniel Collin
- Poway, California, USA

December 6, 2017

A. Daniel,
I'm a little confused as to what your process is. I'm reading this as you receive nickel plated parts, you lay down some EN and use a post dip to blacken, and then powder coat. Is that accurate?

Jameson Grout
- Indian Orchard, Massachusetts USA

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