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Pine Beach, NJ

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Stripping Nickel off Stainless Steel Substrates

adv.

Q. I have a plastic coated cathode shaft which has a stainless steel extension piece added to increase the overall length of the shaft. The extension is covered by a polypropylene sleeve with O-ring to stop the nickel plating from entering the threaded connection of these two pieces. Unfortunately some nickel plating has seeped in and it's now not possible to unscrew the extension from the cathode shaft.

I've been researching various methods of dissolving nickel plating and I can't be sure that the steel cathode shaft and the extension piece will not also dissolve. Can anybody recommend a method to dissolve the nickel plating without affecting the steel? I'm happy to sacrifice the polycarbonate sleeve so this is not an issue.

Darren Steves
- Sydney, NSW
June 15, 2021

A. Hello Darren
Some mixes of Cyanide and Nitrobenzenesulfonic acid salts will strip Nickel safely from steel and stainless steel substrates. Ask your chemical suppliers, as sometimes it is sold as proprietary "stripping salt" to be added to Sodium Cyanide bath.
Good luck,

Leon Gusak
- Winnipeg, Canada

⇩ Related postings, oldest first ⇩

Q. We are an EN shop. We were stripping nickel from a large 4140 substrate. The result was a purple precipitate that seems like it's baked into the substrate now. We have never seen such a phenomenon. We suspect that parts, done previously in the same stripper, with some black oxide film on them may be the culprit. Would anyone have any suggestions as to what it is and how it was caused? As well as how to remove it? Yours truly,

Austin Hirtle
- Mississauga, Ontario Canada
2000

"Electroless Nickel Plating"
by Wolfgang Riedel
en_riedel1991

on eBay or

AbeBooks

or Amazon

(affil links)

A. Sorry, this is a new one on me as well, Austin. If you have a scrap test part, you might try dipping it in chromic acid. For reasons that I don't fully understand, it seems to have some ability to remove stains which nitric acid lacks.

Another thought is that stainless, like titanium, can have a very thin partial wavelength oxide coating which, although actually transparent, looks purple or another color because light bounces off both the surface and the substrate and interferes. You might look at letter 33236 or contact a stainless steel anodizing specialist like Prismatic Stainless Steel [from B&M Finishers, a finishing.com supporting advertiser] to see if they agree what this might be an anodized layer and find out how it can be best removed.

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

Q. I would like to strip nickel (no semi-bright nickel) from stainless steel 304 without effect on substrate other than nitric acid.

Popatbhai B. Patel
electroplating consultant - Roseville, Michigan
2002

A. Contact Macdermid and ask them about the Elnic strip that removes accumulated electroless nickel from stainless steel tanks. It's a hydrogen peroxide / sulfuric acid mixture and works well in place of nitric.

Milt Stevenson, Jr.
Syracuse, New York

Q. Hello ... I want to how can I unstitch a nickel layer from stainless steel. Can you give me a chemical formula?

Sincerely ... I look forward your answer.

Alaattin Tuna
an electroplating company - Turkey
2003

A. Dear Mr. Tuna,

You can strip nickel from stainless steel with 500 ml/l nitric acid(53%).

Kind regards,

Sjamp van Esch
- Eindhoven, The Netherlands

Q. My name's Dante and I'm working on getting a Copper Plating manufacturing line fully running. We've got it to a point where we can produce copper plated stainless steel substrates. However, I'm having a problem where there are some that are messed up, and I can put them through the line again, but I need to strip both Nickel and Copper off the substrate (the substrate is 14" in diameter, it's stainless steel, and gets plated with electroplating, first a thin layer of nickel and then a thin layer of Copper over the nickel). The actual production is doing fine.

However, I am trying to work out how to strip the nickel and copper off the stainless steel substrate. What I usually do is give it to a shop and have them strip it, however the shop is far from where I am and sometimes takes too long. I know that there is a way to strip it, and doing it in house would probably be faster (no other orders in front of mine) and cheaper (less driving and not having to pay someone to do it for me).

I tried to find a simple way of doing it on the Internet and didn't find anything really that would help. There was one thing that mentioned Nitric Acid, but wasn't very informative on the procedure.

If someone could point me in the right direction, that would be great.

Thanks.

Dante Ellis
plating shop foreman - Ventura, California
August 5, 2009

A. First, I would try to figure out what is causing the rejects. Reworks are horribly expensive.
Option 1: to avoid additional haz waste generation, can you machine it off or mechanically remove it? Is grit blasting an option?
Option 2 is to strip it. If your stainless is not in the 400 series, stripping should not put your parts at undue risk.
The safest way is to use proprietary strippers. The better common strippers use cyanide, chromic acid and other nasties.
Some work with the part anodically. With this, you cannot leave it in the tank and go to a long lunch.
Hydrochloric, or sulfuric or sulfuric with peroxide might work on the copper. Nitric will probably work on the nickel. Watch out for copper in the nitric--It Will pit the part at some level. Stripping requires close attention, especially after it has dissolved copper ions in it.

Talk to Metalx (Ronatec.us) [a finishing.com supporting advertiser]. They advertise here and have a nice line of specialty strippers. Tiny company with great customer service.

James Watts
- Navarre, Florida

A. Dante,

You can use nitric acid as you have stated. It is normally used concentrated (about 70%, s.g. 1.42). Just immerse the part until the copper and nickel is stripped. This is done at room temperature. Stripping time will be dependent on thickness of the coatings. Beware, concentrated nitric acid fumes and this process should be done with extraction.

You could also use one of a number of proprietary strippers supplied by companies such as Macdermid or Atotech. Contact your local representative if you are interested in take that route.

Brian Terry
Aerospace - Yeovil, Somerset, UK

A. The mention of nitric probably wasn't very informative because there's not much to it.

Dilute 42 Be nitric acid with no more than 50% de-ionized water, submerge your nickel-plated parts and let sit for a few hours. Nitric at this strength won't harm the stainless. I usually use nitric for cleaning off racks.

There are also some proprietary nickel-strip solutions out there, that are biodegradable. I can't give you brand names, but they work great. They're a bit easier to work with, too. Nitric can be nasty. It smells bad, can react violently (releasing brownish NO2 gas) and it stains your skin yellow.

R.H. Kinner
- Toledo, Ohio

Dear All, thank you for your responses. I will do some more research into the proprietary brands and also see what it would take to go to through the Nitric Acid route.

Dante

Dante Ellis [returning]
- Camarillo, California

Stripping nickel coating from nickel base

Q. Hi
I am an engineering student from Turkey.
I would like to remove/strip the nickel coating (Electroless Nickel) from Inconel alloy 718 (Nickel Base).
What is the suitable stripper to use for removing this coating?

Hope to get some help.
Thanks in advance.

mani arzani
- Istanbul, Turkey,
October 22, 2015

A. Nickel stripping solutions can't tell the difference between nickel plating and nickel alloy so there is no effective way of stripping. If the parts were plated correctly, there should be a copper layer over the alloy 52 for this exact reason.

Casey Weizel, President
Foresight Finishing LLC

- Tempe, Arizona

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