Where the
world gathers for metal finishing
Q&As since 1989


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Want Dark or Black Electroless Nickel Plating

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.

Thanks,

Lee, Min-Gu
- Inchon, Korea
2001

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Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)

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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 21, 2009

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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
April 27, 2009

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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 [on eBay or Amazon] 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 Consultant - Poulsbo, Washington (Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links]            and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links]) 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 April 28, 2009

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Moisture exuding from black electroless nickel plating during bake

Q. My company is manufacturing a part that requires us to black electroless nickel plate 6061-T6 aluminum per SAE AMS2404, 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
November 30, 2017