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topic 57539

Stripping copper plating from steel


A discussion started in 2005 but continuing through 2018

(2005)

Q. Does anybody know how to remove 40-80 microns of copper plate from steel. I am trying to find a way to repair a copper plated tube resistance welded to a mild steel pressure vessel (QTY 40-50). The problem is that when the joint is brazed the copper peels off the steel under the braze. The copper can't be removed mechanically as the wall of the tube is only 1.8mm. Nitric acid has been suggested but this deemed to be too hazardous.

Jude McCusker
Queen's University - Belfast, Antrim, Northern Ireland


(2005)

A. Hello Jude. Strippers can be formulated based on ammonia or based on other oxidizing agents like peroxide. But each user needn't necessarily formulate one from raw commodity chemicals -- the fastest route to a proven stripper is probably to buy it from a specialist like Metalx [a finishing.com supporting advertiser].

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


(2007)

Q. How would I remove copper from a set of steel hinges. I believe the hinges were from the 50's or 60's and I want to reuse them again as steel coloring, not copper. Is this even possible?

Carol Anderson
Remodeling Designer and Contractor - Seattle, Washington, USA



Removing the copper plating from a steel penny

August 10, 2011

Q. Hello, my name is destiny, and my family and I have started the new hobby of coin collecting. We have gathered some hard to come by's and have been researching all the information that we can. Knowing that the 1943 U.S. copper cent is one of the rarest to be in just plain pocket change, we set out to find an explanation of how we may have come across one.

I ran as many "in house" tests as I could, or that I trusted myself without damaging the value. I do know a tiny bit of chemical reactions, so I knew to try the acidic/salt solution. The penny did not produce fizz as the steel does; I tried to use a baby tooth brush with soft bristles to try and get the "so called" age to wear off. When that failed, I turned to the comparison of the two. Copper cents are to weigh in at 3.11g and the steel cents at 2.7g, when I placed this coin on the scale, it read a solid 3.01g. I then referred to a magnet, and as surprised as I pretended not to be, it stuck.

Now that I know it isn't a true 1943 copper cent, I decided to do a small experiment of my own. I scratched the surface of the coin till I could noticed the steel appear. then I took a cotton tipped applicator to the solution and applied it to the new steel surface. again to my surprise, the steel returned to the copper state. after more research I discovered that you can transfer the copper coating of one metal to that of a metal comprised of steel. I am just wondering if this process can be reversed. So if any other "magic steel changing to copper" pennies wander into our family collection, we will know for a fact that this is not the winning token to Disneyland. Any information to solving this "magical mystery" would be great. and it would also give my family a chance to have a little fun with having to do some wonderful, educational, and beneficial experiments.

Sincerely,

Destiny Gilies
newly a coin collector - Grand Island, Nebraska, USA


August 10, 2011

A. Hi, Destiny.

I think you should simply reverse your testing order, and check any "copper" pennies with a magnet first rather than last.

Copper spontaneously immersion deposits onto steel, as you learned, but you can apply electricity to reverse it. If you attach the positive pole of a 1-1/2 volt battery to the penny, and the negative pole to a chunk of copper, or just another penny, and put them in a solution of vinegar with a dash of salt, you can "unplate" a copper plated steel penny.

This doesn't totally solve the problem, though, because "steel pennies" were originally zinc plated. You could see our FAQ, "How Electroplating Works", for simple instructions on zinc plating a penny. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



June 27, 2016

Q. Does anybody have information in regards to a solution that will strip copper plating from ferrous and non ferrous metals?

Bri Thomas
plating shop - Vancouver, BC Canada


June 2016

A. Hi Bri. We have numerous threads here about stripping copper plating, but "ferrous" and "non-ferrous" probably isn't sufficiently detailed (it depends on what the substrate actually is). Further it can depend on why you're stripping it (i.e., what will be the next step after the stripping). Here are a few threads that may help:
- Letter 4476 (stripping copper plating from stainless steel)
- Letter 24642 (stripping copper plating from brass)
- Letter 32636 (stripping copper plating from zinc)

Luck & Regards,

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



December 15, 2017

Q. Hello All,

We (a steel heat treating company) have had issues with stripping our copper plated parts. We only use Cufix-E to strip the parts that we plate. All of our parameters are equivalent to what is recommended in the TDS (Rev. January 2, 2007) and our parts are taking 24-48 hours to strip and are being etched as well. These parts are all different with variable geometries but rarely are larger than a football.

Sam Stull
- Santa Fe Springs, California, USA


January 10, 2018

A. Hi Sam, is this a problem that you have recently encountered, or has it been happening from day one using the Cu stripper? Is is there a copper analysis performed on a regular basis? Is there a dump schedule based on sq footage stripped? We could use some more info in order to help you.

Mark Baker
Process Engineering - Phoenix, Arizona USA



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