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Removing/Stripping Electroless Nickel Plating from Steel-
Q. I am trying to remove electroless Nickel coating and Copper strike from steel without corroding the steel surface. So far my results are very inconsistent: parts cleaned in the same acid vat never look the same. My acid bath is basically Hydrochloric/Sulfuric acids at 1 to 3 ratio with some surfactants and wetting agents. What am I missing in this process?
Thank you in advance,
A. There are a number of commercial strippers for electroless nickel and copper. Both immersion strippers and electrolytic strippers will remove the coating without significantly etching the substrate. My favorite is an ammonium nitrate based solution which operates at a pH of about 6 and is quite fast, especially for EN.
A. Best way to remove plating is let the platers do it. We have to de-plate and re-plate more often then we wish to remember. We send it back to the platers. They in turn use proprietary mixes to selectively attack the plating while leaving the base metal alone. Reverse plating is also another option. Proprietary plating removers are mixtures of acids, highly buffered, with selective chemicals to focus the acids on the platings and leave the parent materials alone. More than that, I cannot help, except to point you to some references. I remember several that covered stripping, but it was not my focus and I took no notes:
2. Electroplating 1978; American Society of Electroplaters McGraw-Hill Book Co, NY ISBN 0-07-038836-0
3. Electroplating Engineering Handbook, 4th Edition 1984: L.D. Durney.
4. Electrodeposition of Alloys, Vol 1 (Principles and Practice) 1963: A. Brenner Academic Press, NY CCN 62-13044
5. "The modern electroplating laboratory manual" [link is to info about the book at Amazon]" 1965: I.C. Armet Robert Draper Ltd, Teddington, England No I.D.
University Libraries are godsends of good data. Good luck.Lee R. Williams
transducers - Costa Mesa, California
A. Dear Sir,
For Stripping electroless nickel from mild steel substrate you can try with mixture comprising 7 parts of nitric acid and 3 parts of acetic acid with /without additives. Care should be taken to check the basis metal often during the stripping process to avoid etching of basis metal.
- Bangalore, Karnataka, India
++ -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. Do you have any suggestions for stripping electroless nickel from a 4340 steel component heat treated to a Rockwell C 50-54 hardness. The nickel plating was applied per Mil-C-26074 [linked by editor to free spec at Defense Logistics Agency, dla.mil], class 2 grade B at .0005 to .0007 thickness.Sam Poutous
Central Point, Oregon
A. Several products exist as the Enstrip EN of Enthone OMI which is used according to the bulletin. Another very easy and quick way to strip nickel is using 100% nitric acid with 10% of acetic acid as inhibitor. The pieces should be baked to eliminate any trace of humidity to submerge them in the solution without to move it neither to take out it until it is stripped. Note, the pieces should be hung.Gabriel Ramirez Nuñez
plating - Toluca, Mexico
April 9, 2010
A. Hi, Sam. The site's supporting advertiser, Metalx, offers their B-9 series of strippers for this purpose. Good luck.
Chemical (Electroless) Nickel Plating
Ted Mooney, P.E. RET
Pine Beach, New Jersey
April 4, 2011 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. I have successfully plated old motorcycle parts with electroless nickel in the past, however my latest attempt is a failure and I believe it is due to one component still having zinc attached which I was not aware of. The result is that the nuts and bolts that I was plating have come out dull grey.
How can I remove this dull grey layer and successfully nickel plate these parts?
Motorcycle restorer - Slacks Creek, Qld, Australia
April 6, 2011
A. Hi Brian,
EN is a bear to remove chemically. You didn't say what the base metal is or what kind of EN (high phos is harder to strip) and an answer pretty much depends on that. If it is steel I would blast it.
electroplater - Galva, Illinois
April 19, 2011
Q. Hi Trent, Thank you for your response which I only just noticed.
I am told by the supplier that the nickel is not high phos, but S nickel rounds. The parts are mainly nuts and bolts with a few small brackets. Sorry, I have no idea what steel they would be. I think they would all be too small to blast.
Since I posted my question to you I have mentioned my problem to others and one suggested I plate over what I already have. I have not tried that as I did not want to ruin the new chemical I have left. What are your thoughts on that suggestion?
Thanks again for your time.
- Queensland, Australia
April 19, 2011
A. S Nickel Rounds are an anode material, so that indicates that your vendor electroplated nickel rather than electroless nickel. One relatively safe chemical option for stripping would be Metal-X B-9+. Overplating is possible, but passive nickel is difficult to chemically activate and would require hazardous chemicals, so I'd hesitate to recommend that you proceed in that direction.
Jon Barrows, MSF, EHSSC|
April 28, 2011
Thank you for your reply Jon. The supplier acknowledges he gave me wrong info. The product is not S rounds but the nickel is at 14%(whatever that means). I strongly suspect there is a problem with the nickel supplied as I purchased a new batch. I split this in half and mixed according to supplier instructions. After a proper cleaning and rinsing and using different stainless containers to plate I got the same poor result. The supplier is investigating my suggestion of problem nickel, but as yet no answer.
I have ordered some Metalx stripper and a different electroless kit from a new supplier and will give that a go. Hopefully it will solve my problem.
Thank you again for your interest.
- Slacks Creek Qld Australia
Q. I am running an electroless nickel company in Argentina. I have a lot of problems to strip the MP electroless nickel from steel, especially I have trouble with nitrided steel or hardened steel. I would very appreciate if someone can give the composition of a stripping bath for steel. Thanks very much. P.S.:actually I'm using a cyanide solution to strip from steel, but it's too slow (really slow)Schonwald Emmanuel
- Buenos Aires, Argentina
A. Hola Emmanuel, We strip ENi from Steel (h13) with proprietary products from our suppliers. They are expensive products, but work fast. Try Enthone-OMI's products. Best regards,Carlos Cielak
plating shop - Mexico City, DF, Mexico
October 29, 2013
Q. Sir, I want to remove electroless nickel plating on mild steel; so what is the procedure?Vikrant Sammanwar
- Pune, Maharashtra, India
November 4, 2013
A. Hi Vikrant. It looks like that question has been answered 8 times on this page. Please try your best to frame your question in terms of the answers provided so that we can appreciate what it may be that you are having difficulty understanding, or what we may be misunderstanding about your situation. Thanks.
Ted Mooney, P.E. RET
Pine Beach, New Jersey