Cleaning heavily tarnished copper

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contrahead
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Cleaning heavily tarnished copper

Post by contrahead »

Forty or fifty years ago, before PVC pipe became so common, buildings were often entirely plumbed with copper- which was more affordable then. Obivously the water lines were plumbed in copper, but oftentimes even the sewer lines in a quality house or building were plumbed with large diameter copper pipe. When remodeling these older building you sometimes run accross this big copper, but it can be corroded. Having some very tarnished pipe laying around I thought I'd try to clean it a smart way rather than wear my fingers to the bone using steel wool and 'Brasso'.
DS.jpg
This picture is of a short piece of dirty old 2 1/2" pipe. It probably came off an old well-head. The smaller pipes in the background are there for color reference.
bb63.jpg
This image shows a coil of copper wire that was used as a sacrificial anode during a previous enperiment. Notice that there were origionally only two sizes of wire, one comming out of the straw - and the rest. The surface of the wire is pitted and in some places it has decreased in diameter or even separated.
bb64.jpg
From this angle the errosion of the copper wire used as an anode can be seen beter. The blue solution is copper sulfate. Origionally a clear solution of mostly water and a little sulfuric acid (left over from filling a new motorcycle battery), this sloution turned blue in a very short time after driving DC current through it.
b667b.JPG
This site explains simple anodizing and electrophoretic deposition. The image above is a test upon cartridge brass (which is about 30% zinc and 70% copper). The first 30-36 cartrige case on the left was the only one that was used as an anode. It is almost eaten through in places and showing odd pink and red colors in other places. The other four cases (used only as cathodes) show various degrees of scale or crust deposits. This coppered scum - some of which comes from the original tarnish on the electrodes, is what stuck to these cases . The effect was interesting but it was not an example of proper electroplating.
DS(1).jpg
This image shows the dirty segment of copper pipe and an equally dirty length of copper wire that is to be used as the other electrode in the upcomming electrolysis.
DS(2).jpg
This shows a large vinegar bottle cut in a way to suport the heavy copper pipe in an upright position. The diameter of the wire coil was enlarged and it was threaded into the bottle. Anode and cathode must make no electrical contact during electrolysis.

<< It seems that this board's editor limits the number of picture uploads to 6 - and I want to post 5 more. I'll try to reply to myself to finish.>>
Last edited by contrahead on Tue Apr 15, 2014 3:11 pm, edited 9 times in total.
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Re: Cleaning copper

Post by contrahead »

DS(3).jpg
This picture shows the electrololysis about 2 minutes underway after turning the power on. Yellow bubles and floatsome are rising to the top while the bottom of the solution is turning a blewish green. For this solution I just used what was handy, which hapened to be a about 1 cup white vinegar left over from the bottle, about 2 cups of brownish apple cider vinegar and a dash of sulfuric acid (about 1/2 cup) which I found from another motorcycle battery filling bottle. The rest of the solution was just clear water and I probably did not need to use so much acid. At 12 volts DC the little computer power supply was quickly overloaded with such a demand and it shut off. At 5 volts the PSU preformed admirably, and quickly. Notice that the polarity is reversed from normal electroplating. The positive terminal is connected to the pipe, making it the sacrificial anode. Had I started the other way around the dirty pipe would have come out even blacker.
DS(4).jpg
This is the dirtiest end of the pipe after just 5 minutes of anodizing. With a strong electrolyte there is no need to run this reverse polarity for very long. You don't want to etch or eat the copper pipe - just antagonize its surface long enough to lift the tarnish away. The inside of the pipe and all those recesses that can't be reached are being cleaned as well. Notice the short, soldered and corroded piece if 1 1/4" pipe...
DS(5).jpg
This looks like the same situation as the previous picture; however the pipe was lightly buffed with steel wool and placed back into electrolysis at normal polarity. After 10 minutes of waiting the pipe was pulled out for this picture. The only real improvment came from the buffing, not by the deposition of very much new copper.
DS(6).jpg
Now the 1 1/4" pipe is wapped with some wire in prepreation to suspend it in the center of the solution. Notice the color of the tin solder.
DS(7).jpg
This last picture shows the same small pipe after 5 minutes of anodizing, a little buffing and then 5 minutes of normal electroplating. The tin solder turned copper colored at one end and black at the other. Apparently electroplating over the solder makes it a little more difficult to sweat the solder off. Since tin solder seems to plate easily though - it might be desirable to electroplate a little this way to hide exposed solder joints.
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Re: Cleaning heavily tarnished copper

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This is genius.
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Re: Cleaning heavily tarnished copper

Post by bellybuster »

please excuse my ignorance as I really don't know but, isn't this just plating over the dirty pipe instead of cleaning off the old gunk?
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Re: Cleaning heavily tarnished copper

Post by Prairiepiss »

I can get it that clean by just dunking it in a 4 to 1 water muratic acid solution. 10 to 15 minutes. And its nice and clean. No need for any electricity. I've had the same bucket for a few years now. Still works great.
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Re: Cleaning heavily tarnished copper

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Edit* nevermind
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Re: Cleaning heavily tarnished copper

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Re: Cleaning heavily tarnished copper

Post by Condensifier »

A citric acid and water solution works pretty well, too, and it's safe to use.
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Re: Cleaning heavily tarnished copper

Post by ga flatwoods »

So does flux.
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I am still kicking.
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Re: Cleaning heavily tarnished copper

Post by BigSwede »

Good stuff!

There's definitely going to be a potent effect depending on the polarity and current. When used as a cathode (-) the metal will tend to take up, plate, with whatever free metal ions are in the solution. If there's copper sulfate in there, it'll plate copper. So you don't want to plate copper on top of tarnish.

When it (the tarnished pipe) is the anode, it's going to deliver metal into the solution... it'll very slowly etch, eat away. I can see using the anode action to lift off a layer of crud and a few microns of copper. Definitely worth more experimentation.

I'm still a fan of simple pickling. So many easy options. I like phosphoric and citric acids for safety and non-toxicity. Sulfuric and muriatic (HCl) also work well. Don't use nitric, it's toxic.

Proportions that work
15% phosphoric
10% sulfuric
5 to 10% muriatic. Pool store muriatic is 32%

You can always go lower. Temperature is a big factor, hotter = much more aggressive. I think a great experiment would be to add electricity into a normal pickling operation.
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Re: Cleaning heavily tarnished copper

Post by W Pappy »

Vinegar salt and flower paste is what I use. Apply with a paint brush and it cleans the copper to a nice salmon pink in a just a few strokes of the brush.
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Re: Cleaning heavily tarnished copper

Post by Cu pipe »

Learned 4 ways of cleaning copper....Danm , I love this forum.. :D
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Re: Cleaning heavily tarnished copper

Post by Saltbush Bill »

Seems like a huge amount of rigmarole to go through just to clean some copper, Dump the copper into a tub of dunder or backset for a few hours and the same thing happens with a lot less hassle.
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Re: Cleaning heavily tarnished copper

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Rigmarole = overthinking.
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Re: Cleaning heavily tarnished copper

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Hot slops

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Re: Cleaning heavily tarnished copper

Post by contrahead »

LWTCS wrote: Tue May 18, 2021 3:49 am Rigmarole = overthinking.
(Assuming backset hasn't been neutralized by a bunch of pesky oyster shells).

It seems like a waste of time to criticize someone for what they proposed seven years ago. Yes, overkill perhaps. But the information offered back then could still be useful to someone with an open mind. Someone with imagination might perceive or come to realize that they might be able to deposit copper over unseemly blemishes and soldering joints by reversing the electrical polarity.

Rigmarole or not, knowledge is not a waste. Sometimes it's even handy. For instance, ammonia which is an alkaline and the polar opposite to any of the solutions ever mentioned in this old thread; might even be a superior tarnish remover, to acid. Just drop some old brown pennies into some ammonia for 24 hours – and check it out. Oh: and American pennies made after 1982 are zinc slugs electroplated to a depth of 20 microns, before they are stamped. Some people even consider electrolysis an interesting phenomenon.

An inquisitive mind might wish to know that the 'tarnishing of copper' is caused by an electrochemical interaction between molecules on the surface of the metal and molecules in the surrounding air. The interaction of copper ions with oxygen ions is also enhanced by the presence of moisture. But copper tarnish can also be caused by ion exchanges with other airborne chemicals like carbon dioxide, sulfur dioxide, and hydrogen sulfide.

I don't know everything; I'm just a babe in the woods. Now I feel almost apologetic. Not contrite that I began the post, but that I was naive enough to enthusiastically share information new to me; with so many that already know all the answers and who don't need new ideas.
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Re: Cleaning heavily tarnished copper

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contrahead wrote: Tue May 18, 2021 9:47 am
LWTCS wrote: Tue May 18, 2021 3:49 am Rigmarole = overthinking.
(Assuming backset hasn't been neutralized by a bunch of pesky oyster shells).

It seems like a waste of time to criticize someone for what they proposed seven years ago. Yes, overkill perhaps. But the information offered back then could still be useful to someone with an open mind. Someone with imagination might perceive or come to realize that they might be able to deposit copper over unseemly blemishes and soldering joints by reversing the electrical polarity.

Rigmarole or not, knowledge is not a waste. Sometimes it's even handy. For instance, ammonia which is an alkaline and the polar opposite to any of the solutions ever mentioned in this old thread; might even be a superior tarnish remover, to acid. Just drop some old brown pennies into some ammonia for 24 hours – and check it out. Oh: and American pennies made after 1982 are zinc slugs electroplated to a depth of 20 microns, before they are stamped. Some people even consider electrolysis an interesting phenomenon.

An inquisitive mind might wish to know that the 'tarnishing of copper' is caused by an electrochemical interaction between molecules on the surface of the metal and molecules in the surrounding air. The interaction of copper ions with oxygen ions is also enhanced by the presence of moisture. But copper tarnish can also be caused by ion exchanges with other airborne chemicals like carbon dioxide, sulfur dioxide, and hydrogen sulfide.

I don't know everything; I'm just a babe in the woods. Now I feel almost apologetic. Not contrite that I began the post, but that I was naive enough to enthusiastically share information new to me; with so many that already know all the answers and who don't need new ideas.
I have to admit, reading the thread made me think about that after seeing what one member did to copper plate all of his tri clamps.
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Re: Cleaning heavily tarnished copper

Post by LWTCS »

Came across as critical did it? I do apologize.
Meant to come across as a way to simplify a process that really doesn't need to be that complicated.
And also to recycle materials that may otherwise be considered stillage waste.

All of the other info in the thread certainly is informative. It's just for our purposes,,,, the easiest solution is what goose and Bill recommended.
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Re: Cleaning heavily tarnished copper

Post by Deplorable »

Hot backset, and a worn out scotch-brite scrubber are what I use to clean copper when it starts to get splotchy looking. I prefer the darker orange patina to the more pinkish hue of clean copper, so I try not to leave hand prints on my stuff, and just let it oxidize. I don'l want it to get as nasty as Jesse's still on the u-toobs. The only thing I keep very clean is my home made copper whiskey thief.
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Re: Cleaning heavily tarnished copper

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The dialog reminds me of that scene in Sling Blade where they at the small engine repair shop and the fellers was just over thinking.

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Re: Cleaning heavily tarnished copper

Post by Twisted Brick »

Thanks Contrahead,

I was just looking at YouTube videos using electrolysis to clean up cast iron pans and researching the (negligible) benefits of using Sodium Carbonate (Na2CO3) vs Sodium BiCarbonate (NaHC03). With copper, it appears vigilance would be needed to avoid surface etching or pitting, but I'm drawn to try cleaning up some older rust-worthy tools just because, and that rigging up the process is super-simple.

Given that we all learned that an acid (lemon juice, coca-cola) can render a tarnished penny looking shiny and new, pointing out that your electrolysis process to clean copper pipes may be tedious or excessive, is, well, obvious.
Deplorable wrote: Tue May 18, 2021 10:17 am
I have to admit, reading the thread made me think about that after seeing what one member did to copper plate all of his tri clamps.
I admit those copper tri-clamps looked sexy. I just assumed they were done by an electro-plating outfit and pretty pricy.
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Re: Cleaning heavily tarnished copper

Post by Saltbush Bill »

Twisted I restore and clean many old rusted tools each year for resale at swap meets.
Hot slops will do the same thing for your tools.
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Re: Cleaning heavily tarnished copper

Post by Deplorable »

Right? But to be able to do it with a piece of sacrificial copper and some acid at home?
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Re: Cleaning heavily tarnished copper

Post by Yummyrum »

BigSwede wrote: Fri Apr 18, 2014 7:37 am Sulfuric and muriatic (HCl) also work well. Don't use nitric, it's toxic.
Just to clarify what Swede was saying , Concentrated Nitric acid will react very quickly with copper . The reaction will release huge plumes of extremely corrosive Nitrogen Dioxide gas . It will destroy lungs very efficiently .
The copper will turn into Copper nitrate solution .
A piece of copper will be literally eaten up in a matter of minuates . :egeek:

When it comes to cleaning copper , I usually want it done quick , IE , I’m building something and want to clean as I work . So for me , its a 10% solution of Sulphuric acid . I’ve had the same bucket of it fir years now and have had to change the bucket as it was starting to brake down .
Weaker acids and Dunder are fine if you have time . :thumbup:
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Re: Cleaning heavily tarnished copper

Post by Windy City »

I generally don’t end up with “hot slops” due to the fact that I distille on the grain. My “hot slops” generally go down the drain as I am on a Chicago sewer system.
But I do enjoy a great build and predominantly clean my creations with a 10% citric acid solution.
I had been buying my citric acid from
https://www.bulkapothecary.com/raw-ingr ... tric-acid/
But with everything going up in price, I was amazed that this has doubled in price.
I used to buy 200# @ approximately 250$ US
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Re: Cleaning heavily tarnished copper

Post by Rrmuf »

I am on the "just dump it in the backset" side, but very cool topic. :-)
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Re: Cleaning heavily tarnished copper

Post by cranky »

Years ago someone gave me 150 lbs of citric acid so of course that is what I use for copper but I also use it to derust car parts. Reading through this thread I'm wondering how well backset might work on car parts.

I'm also thinking maybe I should electroplate my spare tailgate and hang it on the wall :problem:
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Re: Cleaning heavily tarnished copper

Post by Twisted Brick »

Saltbush Bill wrote: Tue May 18, 2021 12:59 pm Twisted I restore and clean many old rusted tools each year for resale at swap meets.
Hot slops will do the same thing for your tools.
Rrmuf wrote: Wed May 19, 2021 4:16 am I am on the "just dump it in the backset" side, but very cool topic. :-)
Gotta try this. Is backset more effective hot than at ambient temp?
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Re: Cleaning heavily tarnished copper

Post by Saltbush Bill »

Twisted, for cleaning tools Ive always used it cool/ cold.
Ive used it both hot and cold on still parts and both work..... hot maybe slightly more efficient.
For more on the subject read this. https://homedistiller.org/forum/viewtop ... =7&t=54523
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Re: Cleaning heavily tarnished copper

Post by Deplorable »

I'm gonna have to soak my mole traps in backset and see how it does.
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