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Stripping nickel plating from aluminum -- Q&A, Problems & solutions

adv.
Metalx nickel stripper

Nickel stripper for aluminum, question about ingredients

Q. Dear fellows,

I am searching for a nickel stripper to deplate cast aluminum dies. Spa plating and Metalx don't deliver to Europe. I also understand they don't make their formula public.

So I spent some time regarding commercial stripper solutions and found out that those strippers are based on [sorry: paragraph about five ingredients and the roles of each deleted by editor]

I am not a chemist. But sulfuric acid and hydrogen peroxide as oxidizer works also, but attacks the aluminum quite hard. May it work, if I add a corrosion inhibitor?

I would prefer an immersion stripper. Electro stripper attacks the substrate too hard. The parts to be deplated are not fully plated. So some areas are of the aluminum are exposed to the solution from the beginning.

Thanks

Chris Seidl
- Vienna Austria
May 12, 2024


A. Hi Chris. We appended your inquiry to some earlier discussions on the topic which you may find helpful (nitric acid and water may be all you need). But there may be other suppliers who offer commercial immersion strippers in Europe if that interests you.

Apologies, but we can only print your list of ingredients for commercial strippers and their functions if you cite the published places where you found each of them (textbook name, name of article, patent, suppliers technical data sheet, SDS, etc.)

The reason is that we don't know internet posters (if I'm not wrong, the name you are using is fictitious), and if you contribute this, and a 2nd person adds that, and a 3rd person says thus and so ... somewhere along the line someone's knowledge may have been illegitimately obtained (a disgruntled former employee posting with a fictitious name, etc.) and the posting might comprise anonymous crowd sourcing of industrial espionage. :-(

Reverse engineering is usually considered fine when done right, but certainly not when publicly posted by an essentially anonymous group :-)

Sorry again, and Regards,

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


Q. Hi,

I am not either a disgruntled former employee nor spying.

You can find dangerous ingredients in SDS and I found a patent in google. These are alkaline strippers, based on sodium carbonate.

Patent number US4720332.

In Europe it's forbidden to own nitric acid more than 3%. The reason is you can make explosives from this. If someone intends to do this, he will get the ingredients, forbidden or not.

This is why I am searching for an alternative.

Chris Seidl
- Vienna / Austria
May 15, 2024


A. Hi again. Indeed, that is a 1986 patent, now long expired, so you are welcome to use it. The preferred embodiment is supposed to work -- because a fully disclosed workable answer is the payment the public is entitled to receive in return for bearing the costs of protecting the patentee for 20 years. But even still, we can't publicly discuss the formulation of proprietary products.

I understand that you prefer to not use an electrolytic stripper, but sulfuric acid electrolytic strippers are discussed on this page if you find no workable alternative. Good Luck,

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







⇩ Related postings, oldest first ⇩



Q. I'm trying to strip nickel from a couple of improperly plated aluminum parts. The local chrome shop dipped it and removed the chrome, but told me to SAND and POLISH off the nickel! I've been able to carefully peel off some but not all of the nickel. Is there a chemical or electrochemical process for removing the nickel plating?

Thanks,

John Simpson
- SW Ranches, Florida
2003


simultaneous replies

A. Concentrated nitric acid will do it without destroying the alloy in most cases. You will need proper protective equipment and good air flow as it will emit NOx!

For small areas, try a swab. It will last for a minute or so and then you will need another swab. Properly dispose of your refuse. It is hazardous.

James Watts
- Navarre, Florida

Ed. note: James corrects his statement about NOx below.

A. Try nitric acid say 50% by vol. Be careful-- wear protective gear and avoid breathing fumes.

Geoffrey Whitelaw
Geoffrey Whitelaw
- Port Melbourne, Australia


A. I suggest you go back to the local plating shop and teach them how to strip in the above mentioned nitric acid solution. I would strongly suggest that you do *not* mess with concentrated nitric and the hazardous waste you will produce once you load it with nickel.

Jon Quirt
- Minneapolis, Minnesota


A. The large gunsmith supply companies carry a nickel stripper that works quite well. The parts that need to have the nickel removed just need to be immersed in the liquid. It's the best way I've found to remove nickel without a lot of polishing but it only comes in one gallon quantities so it's not meant for large jobs.

Brian F Bonser
custom weaponry - Stuart, Florida
2003

Ed. note: Thanks Brian. Gun shops probably have it only in 1-gallon containers because of the type of the customers they serve. 55-gallon drums and pallets loads are available from suppliers to the metal finishing industry.

thumbs up sign Just to let you guys know. I have successfully removed a lot of chrome and nickel with the techniques listed here. I'm lucky enough to have access to a large supply of sodium Hydroxide and Nitric acid. I have been using them for years at my Job. (with the proper training and safety gear). After buying an old motorcycle I was look into into ways of removing the chrome, then nickel then polishing up the aluminum. and WOW...it worked great. That is AFTER I destroyed a small pc. trying to sand and pick it off.

THANK YOU VERY MUCH.

Brian

Brian Maty
- Scranton, Pennsylvania USA
2006


A. 50% tech grade sulfuric acid (66 degree sulfuric acid) and 50% water using electricity will take off your nickel without hurting your aluminum. You can use a battery charger [on eBay or Amazon affil links] as a rectifier. If the part has copper on it depending how much build is on the part it should remove it also. Nitric acid will do the job the same way without electricity -- make sure you don't put steel in nitric acid, bad* chem reaction. good luck

Mark Ryder
- Dayton, Ohio
August 10, 2008

Ed. note: * - by bad reaction, Mark means the solution will evolve copious clouds of toxic NOx. So, to repeat then, keep nitric acid away from steel!



Multiple threads merged: please forgive chronology errors :-)



Stripping Gold and Electroless Nickel from Aluminum Alloys

I am looking for suggestions for an acidic, gold stripper that will not harm/alter aluminum alloys. I have an aluminum alloy part (made from Osprey CE9) that I plated with electroless nickel and gold. My customer discovered that the part configuration was machined wrong and it went back to the tool room where modifications were made to the plated part. I now need to replate the machined surfaces of this part for solderability reasons. I would like to strip the part back to base metal before replating, but Enstrip L-90 that I had used in the past to strip this combination of plating from aluminum has been reformulated. It still does a good job of stripping nickel, but it will no longer strip the gold plate, too. I don't have time to allow it to undercut the gold plate by mining out the nickel layer. I fear if I try to mask off the existing plated surfaces I will have problems at the interface between the two plated areas from under cutting of the exposed nickel plating layer when the part goes back through the aluminum preplate cycle which involves nitric and nitric/ammonium bifluoride solutions prior to zincate coating.

Terry Mooney
- Kansas City, Missouri, USA
2006





Multiple threads merged: please forgive chronology errors :-)



Q. Hi,
I am an engineering student from Malaysia. I am conducting a research on: can sulfuric acid be use in etching to remove a nickel plated aluminum disk? I would like to remove the nickel but not the aluminum from the disk.
1. what is the concentration of the sulfuric acid for etching? ( is it 30% )
2. do I need to mix the acid with water?
3. is the method the same as anode and cathode?
4. how to calculate the time for the etching process?
5. what is the suitable container to use for etching?

Can anyone give the procedure or idea to conduct the experiment above?

Hope to get some help..
Thanks in advance.

Lee Chee Hun
student - Malaysia
2005


A. Nickel can be stripped from aluminium using the Laybere solution; this a mixture of 3 parts of conc. sulfuric acid to 2 parts of water. It is used at room temperature with an applied anodic current of about 40 A/ft2. Your container will depend on the size of your parts, but I see nothing wrong with a glass beaker [beakers on eBay or Amazon affil links] if it is of the correct size. If you need something bigger, use a PVC, polypropylene or rubber lined steel tank. As far as the processing time is concerned - it all depends on how much nickel you have to remove and what the temperature is. Now that you have been told what to do for your project, go and do some experiments for yourself, but don't forget to give due reference to the sources of your information as it would be most unethical to claim the credit yourself.....

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


A. I doubt if it will work. It will also depend on what the aluminum alloy is.
Look at concentrated nitric acid. One notch below red fuming. Regular nitric that most people would use commercially has too much water in it. The part has to be absolutely dry when you put it into the acid. Note that it will slowly absorb water from the air and you will at some point have etched parts.

James Watts
- Navarre, Florida

Ed. note: James corrects his statement about NOx below.

"Sulfuric acid Manufacture"
by King, Moats,
& Davenport

sulfuric_acid_mfg_2013
on AbeBooks

or eBay or

Amazon

(affil links)

Q. Hi,

please do help me out with my experiment, as the deadline is next week. I have no idea whether sulfuric acid can be used to etch (remove) the nickel plated aluminum disk. I only want to remove the nickel not aluminum. Currently, I am using aluminum potassium sulphate to etch (remove) the nickel.

Thank you Trevor Crichton & James Watts.

Dear Trevor Crichton,
I will definitely acknowledge the ideas given by you in my project. will sulfuric acid perform better that aluminium potassium sulphate to etch the nickel plated aluminium disk?the area that I would like to remove is about 1 cm x 1 cm only. I can use the Laybere solution as a guideline?

Mr James Watts,
Based on your response, do you mean that sulfuric acid will not be able to etch (remove) the nickel plated aluminium disk? And nitric acid will be a better solution?
'One notch below red fuming' I don't understand this statement -- can you explain further.

hope to hear from both of you soon.thanks,

Lee Chee Hun [returning]
student - Malaysia


simultaneous replies

A. Laybere solution has been well known for many years, so there is no reason why it can't be used as a benchmark. I think you will find the sulfuric acid bath will react faster than aluminium potassium sulphate. Be careful of the sulfuric acid as it is very corrosive.

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


A. My company regularly uses a 50% (vol) solution of Nitric acid, and DI water to remove nickel from aluminum. This solution will hardly attack the Aluminum substrate, and works quite well.

Marc Green
Marc Green
anodizer - Boise, Idaho


thumbsdown OK, my head was somewhere other than firmly attached to the neck. The procedure that I talked about was for removing EN from steel. My bad.

In another letter, an author talked about using 12% sulfuric acid with peroxide for removal of EN. Do not remember the substrate.

James Watts
- Navarre, Florida


A. James, the sulfuric acid/peroxide mix is pretty potent and will take off most metals - I have used a similar formulation for dissolving both nickel and copper, but it will chew up any metal substrates if you're not careful!

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


"Sulfuric Acid Use and Handling"
by Oscar T. Fasullo
sulfuric_acid_usehandling1965
on AbeBooks

or eBay or

Amazon

(affil links)

Q. Hi,

thanks so much for the positive responses.

As the deadline had been extended, I hope to try out the two experiments using sulfuric acid and nitric acid.

I am trying to source for an ampere meter. (Do I need it?)
This is how I plan to conduct the experiment:
1. I will conduct it in a fume cupboard.
2. pour 150 mL of H2SO4 to 100 mL of DI water in a beaker.
3. after mixing it, will place a dummy disk in the beaker.
4. the Al disk ( 95 mm diameter ) will be placed inside the beaker.
5. the current is about 9 V. Anode will be clip to the Al disk, while Cathode will be connected to the dummy disk.
6. etching time still unknown... (can it be calculated/ measured?)

Please do correct me if my procedure is wrong.
How will the ampere meter come to good use? how will it function?
Any other better suggestions?

Thanking all of you in advance.

Lee Chee Hun [returning]
student - Malaysia
2005

Ed. note: Ampere-hour meters are available from all suppliers of plating rectifiers and power supplies.

Q. Hi,

Any suggestions / ideas regarding to the procedure that I am going to use? is the method correct? as I hope it is safe to conduct it.

Please let me know, thanks again.

Lee Chee Hun [returning]
student - Malaysia


A. You can use electrolytic etching -- this process is much safer than H2SO4. Slightly acidified nickel sulphate solution can be used as electrolyte, object=anode, platinized titanium or stainless steel=cathode.

Good luck!

Goran Budija
- Cerovski vrh Croatia


A. You will need an ammeter to tell you the amount of current being passed. You will also need an accurate clock to tell you the time spent; I suggest a stopwatch. Your process looks basically sound, but I suggest you check with your supervisor before doing it - he knows your abilities and the abilities of your classmates and the equipment. Furthermore, he is responsible for you!

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


Q. Hi,

Thanks, I had tried out the experiment with sulfuric acid, it's a bit dangerous as sulfur gas was released during the etching process. Will nitric acid be the same as well?
Additionally, I would like to add a system (timer) that can cut off the current once the etching process is finished.
Can it be done? with this, I will try out on different surface size to etch, so I can set approximately the time needed to stop the current once the process is finished.
But I am concern that the aluminum potassium sulphate which I am currently still using will degrade after 2 rounds of etching. the time set for the 1st round should be faster compared to the 2nd round,right? will it be the same as well for sulfuric acid?

thanks again for replying.

Lee Chee Hun [returning]
student - Malaysia


A. Hi, cousin Lee.

It would be dangerous to conduct experiments except under a lab hood, and without wearing the correct PPE experiment, or without proper training and supervision. People on the internet, who you don't know and who don't know you, your facility, or your training level, can't be sure about the safety of a proposed experiment. As Mr. Crichton noted, your supervisor is the one who must be asked these questions and who must supervise you during it. Good luck, and stay safe.

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




sidebar

A. If you want to remove the nickel from hard drive disks you cut the disks up into 1/4 inch strips and soak it in HCl or muriatic acid this will dissolve all the aluminum base metal and all you are left with is the nickel platinum cobalt alloy thin film. I do this all the time and sell the foil on eBay as a platinum alloy. there is a fast reaction at first it takes about a week for me to dissolve 60 disks at once I hope this helps.

William Thompson
- Watson, Sask, Canada


A. You could use household bleach [adv: bleach/sodium hypochlorite in bulk on eBay or Amazon affil links] , it works on the disk.

theodorus schuurbiers
- Curacao Island, Caribbean


thumbs up sign Thanks William and Theodorus. But you folks are talking about scrapping, whereas in this case Lee is looking to remove the nickel coating without doing damage to his aluminum disk.

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




A. Hi all..

If you got NiCr to be stripped,

you shall remove the Cr with sodium carbonate/washing soda [on eBay or Amazon affil links] anodic at 3 ADM...after that only, you strip the nickel by sulfuric 60%.

To strip nickel from Aluminium disk, you need 70% dilution from 68% nitric acid by dipping process. The nickel will be removed, the fumes might be a bit danger so be careful. To create process inhibition you may add sulfuric acid at 5% dilution.. but the more you put it will slow the process.

Monggo luton
- Selangor, Malaysia
November 12, 2009




Q. Hi, I am also an engineering student from Malaysia. Currently I'm doing research on how to remove nickel from FCC Catalyst. For now, I only get 63% removal by using 10M sulfuric acid with 30 °C in 120 RPM shaker.

1) Can anyone suggest how I can increase the percentage removal?
2) What is the interaction between nickel and sulfuric acid?

Thank you.

Nur Fadhilah bt Abdul Rahman
Malaysian Student - Kuala Lumpur, Malaysia
May 12, 2013




Q. I bought new spare part aluminium alloy (Al+Mg alloy) and let it be nickel plated. They did not remove oil from alloy correctly and it made bubbles on nickel layers (on smooth milled surfaces). How can I fix this? Do you recommend to remove nickel and then replate it? How? I am afraid of alloy immersed in strong chemicals. Or mechanically? Sandblasting? Can you help, please? Thank you!

21020-1

Jan Bzan
- Prague, Czech
June 17, 2020


A. Hi Jan
Yes the nickel plating must be stripped and re-done. We added your inquiry to a thread on the subject which suggests a number of different ways, but a proprietary nickel stripper is probably safest. Good luck.

Regards,

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


A. Dear sir if you use nickel stripping, the part will be little much eroded in microns. Again you have to polish it. After this on aluminium they are doing zincating process, then ENP or Bright nickel. If zincating solution is not well maintained this problem occurs. It's not only due to cleaning ... better to try Electroless nickel on zincated surface. You'll get better adhesion and corrosion resistance too due to phosphorous content in ENP. It has 3 grades: use high phosphorous grade.

Vasanth Karunakaran
- Chennai, India


Q. Dear all,
I used 65 % Nitric acid to strip down nickel plating from my aluminum alloy. I did not know how long it should be immersed in this solution. Is it for a minutes, hours, days? I let it in acid for a one day (maybe too long) and there is a pitting corrosion on some smooth surfaces. It worked perfectly for a nickel etching. But this pitting looks not so nice. What was wrong? Unknown alloy behavior? Too long etching time? Thank you for your help!

Jan Bzan [returning]
- Prague Czech Republic
August 16, 2020


A. Dear Jan,
One day is too long for nickel strip using nitric acid. Few minutes should be enough. Clean the part from oil, immerse in nitric acid in well ventilated area for 5 minutes and check. Continue with 5 minutes immersion cycle until the deposit will be dissolved.
Good luck!

Alex Sirota
- Lod Israel




Q. You say to use 3 parts Conc. Sulfuric acid to 2 parts water ,
At what Mol weight or % Sulfuric acid is considered concentrated?

Terry Way
hobbyist - Winder, Georgia - USA
January 7, 2022


A. Hi Terry. Trevor's postings were from 17 years ago so I don't know if he'll see yours and follow up, but in this context "concentrated" means 'as concentrated as possible/practical', i.e., 98% / S.G. 1.84 / Molarity 18.4.
Some people might say concentrated sulfuric acid is only 96% for some practical reasons, but when you're diluting with water that way, whether the acid was theoretically 98% or 96% really doesn't actually matter. Good luck!
I hope you and other readers are attentive to the safety warnings he repeats 3 times in the course of the discussion.

Luck & Regards,

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


adv.
Metalx nickel stripper



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