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Need corrosion resistant, RoHS compliant, conductive, black coating

Q. Need to blacken reels of a copper strip 1/8 in wide by 0.04 in thick.
Resulting black copper will need to be scratch resistant and most importantly, electrically conductive.

Will need to blacken over 10,000 ft of copper strip, split into several spools.



Gerard Szejnberg
lighting - Montreal Quebec
June 30, 2021

A. Hi Gerard. It will depend on cost sensitivity and 'how conductive is conductive?'.

If you need a quite perfect tarnish-free & oxide-free surface, then only a precious metal like black rhodium [adv: black rhodium plating solution on eBay or Amazon affil links] or black ruthenium can provide that. If good conductivity, but not low-voltage low-amperage "contact" quality is required, black chromium plating might fill the bill; it's hard and scratch resistant too. If more 'iffy' contact resistance is permissible, zinc plating with a black chromate, or black nickel plating might suffice.

I'm not aware of any black oxide / chemical blackening coating that would be conductive and scratch resistant, but there might be a proprietary one out there somewhere :-)

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
July 2021

July 5, 2021

Q. Hi Ted,

Thanks for your input.

We are on what I think might be considered a low voltage / low amp application (24 to 48v, at a max of 4 amps)...
Is this indeed low, or are you talking mili-volts, mili-amps?

Maybe you can help clarify some of the below:

1- I had seen all the info on the forum before, and found that black chrome was an option, but unless I am wrong, it cannot be done on reel to reel applications. Is this so?

2- I did a sample with black zinc. I don't know if it can be done with other methods than black chromate. That said the result I got looked good but was non conductive.

3- Finally, black nickel plating seems to produce a conductive finish when it is plated with an electrolytic method, but non conductive when it is produced with electroless. To my understanding, this cannot be done in reel to reel either.

We are also looking at using Ebonol C, which apparently does give a conductive finish, and might work on reel to reel, since there is a product that only needs about 30 to darken. Now I need to find someone to run a sample for us!


Gerard Szejnbergret
- Montreal Canada

A. Hi Gerard. I'm no electrical contact expert, but I do notice that gold is used for digital signals whether on a circuit board, an old Atari cartridge or a new iPhone lightning connector because precious metal don't oxidize or tarnish -- but nickel plating, which does tarnish, is fine on charging contacts for cordless phones, flashlights ... anything relatively low power and low voltage but above digital signal levels.

Suresh mentions a conductive topcoat after black chromate which I am unfamiliar with, but which apparently exists and may serve you.

I don't think there's a technical reason that black chromium cannot be plated reel-to-reel, or electroless nickel either. However, there is the logistics problem that you have to find a jobshop who does it, and they may not exist, since continuous plating jobshops are few :-(

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
July 2021

⇩ Related postings, oldest first ⇩

Q. I have had requests for a coating that achieves the following:

-Corrosion Resistant
-RoHS Compliant
-Black in color

Is there something that anyone can recommend?

Michelle Kanganis, Vice President
metal processing - San Diego, California, USA
June 5, 2008

A. Hi, Michelle. It's not cheap, but black chrome plating is the first thing that would come to my mind.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
June 5, 2008

A. There are a lot of graphite lubricant lacquers on the market that fit this spec - you don't say what wear resistance or conductivity you need - graphite paint is easy to source.

C Souter
- Driffield, East Yorkshire, UK
June 6, 2008

A. M'am can you try zinc iron plating with trivalent black passivation and conductive top coat

Suresh Reddy
- Bangalore, India
July 26, 2008

Q. Hi,

I'm trying to find a finishing process that will allow me to coat some brass parts that I am making leaving them black colour, and would really appreciate any help! In addition to the colour the finish needs to be fairly hard wearing and electrically conductive! Something which I am really struggling to find!!

If it would help with coating, then the part material can be changed from brass to pretty much anything other metal.


John Blanch
- London, England
October 10, 2012

December 28, 2012

A. If you can change the base metal a lot of possibilities in Plating exist; the same cannot be plated economically over brass.

For brass you can use a thin zinc flake based coating and black topcoat from the same family of ZF topcoats that bond pretty well on brass and resist post working to some extent and solvents, fuels, refrigerants to a large extent.

Khozem Vahaanwala
Khozem Vahaanwala
Saify Ind
supporting advertiser
Bengaluru, Karnataka, India
saify logo

A. Black chrome plating (copper-nickel-black chrome) isn't cheap, but would probably be good.

Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
December 30, 2012

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