Copper conservation help needed

I’ve got an 1811 Bristol Brass and Copper Penny that’s got some damage from tape, as well as some other gunk. I’ve let it sit in distilled water for a couple hours with no change. What’s the best way to conserve this coin?

https://en.numista.com/catalogue/pieces45161.html

@GDJMSP @BadThad @Eduard @Kentucky @Conder101 @desertgem

 

Log in or Sign up to hide this ad.

I don't know if this would work on your penny, but the following medal received a good soak in 100% virgin olive oil.

Before


After

 

Well, yours looks fantastic. I definitely think I’ll finish whatever I do with olive oil. I’m wondering how to get the glue remnants off. Maybe really hot water ran across it?

 

acetone will remove tape residue

 

I’ve always heard conflicting information about acetone on copper. Some have warned it will turn the copper pink. I guess I was hoping for someone who has experience in the matter to give me their two cents. Have you used acetone on old copper? I’m not 100% sure it matters due to the fact that there are already pink spots on the coin, but I wanted to be sure before dipping it in acetone.

 

@Seattlite86 Acetone on old copper could turn your coin into a "colorful Easter Basket"...not always but I've seen it. I would try distillated warm water.

@cpm9ball I never tried olive oil like that...looks really good.

 

I've never had a bad experience with old copper and acetone.

 

Never had problems with acetone on copper either.

 

I think the rumor about acetone on copper should actually be attributed to lacquer thinner. Don't make that mistake. The main ingredient of lacquer thinner is indeed acetone, but it has other stuff that is not so good for copper and will turn it "pink" by removing the top oxide layer.

 

One more vote here from the “never had a problem with copper and acetone” camp.

 

I've had a problem with bronze and acetone, but only twice. Can't explain it, but it happened.

@Seattlite86, try xylene as an alternative to acetone for the tape residue.

After that, your coin needs a Verdi-Care treatment. Great stuff.

 

There has been 1 paper that seems to indicate that a high water vapor in the air, high UV radiation similar to that at 20,000 feet , can allow acetone to react to copper alloys as it doesn't seem to otherwise. There are other quirks to the experiment also. I live is a desert region at minus sea level altitude so I do not limit my use. YRMV. Jim

 

"Quirks" is a good way to describe my two bad experiences with bronze and acetone. One was a 1942 British India 1/4 Anna...turned almost as pink as cotton candy. Don't recall what the other coin was.

I've soaked hundreds of circulated bronze coins in acetone with no issue whatsoever. I can only assume that in those two instances, I was dealing with either a metallurgical anomaly, or some kind of "perfect storm" of environmental conditions that produced those unpleasant results.

I will still occasionally put a bronze coin in acetone, but only for short periods like 30-60 seconds. Otherwise, I've found that xylene is a safe and reasonably effective substitute for removing organic gunk from coins.

 

Thanks for the feedback folks. I’m going to start with distilled water, go to acetone, and back to distilled water. I’m here in Germany and can’t seem to find xylene available. I don’t know where I put my Verdi-care, so I’ll have to use 100% extra virgin olive oil as the final bath. I’ve read posts here, specifically from @SuperDave (still not sure what happened to him) that day 30 minutes each. I’m not certain that’s going to be enough time to get the residue off. What are your recommendations for time lengths and how often to swap out the acetone. I have plenty, so this is really about doing this right.

 

This is my experience with acetone:

I regularly use acetone on copper coins, ancient or new, to remove unsightly deposits. It has never harmed any of my coins. I do a first dip in clean acetone for 15-20 minutes to observe the effect. If progress is observed, I may continue the dip or not, as needed up to 1-3 hours. I have read about people dipping for 24 hrs as well. I have never tried that on copper, only on silver, with no problems.
Always handle acetone carefully. Wear gloves, and do not breathe the vapours.

Acetone is a solvent with polarity such that it can remove both non-polar (oils, organic debris), as well as some polar deposits (pvc residue may fall into this category, I believe). It will not chemically interact with a surface, so it does not combat corrosion, verdigris, etc.
If acetone will not work, I then try toluene as it has a more pronounced non-polar character - I have been able to remove lacquer on lacquered coins that way which acetone will not dissolve.
Because of the oil removal, acetone treatment may leave a coin looking drab and lifeless. Be aware of that.

It has been reported that under the influence of light and heat, acetone may degrade and form acetic acid (?), which will react with copper. For this reason, to be on the safe side, I avoid using acetone under direct sunlight, and also limit the time of exposure.

 

Thank you for the insightful reply. I’m very intrigued by old copper coins and this one seems like it has a story to tell.

I’m not sure why I couldn’t find xylene at the gigantic Home Depot Type Store that I was at. I even asked the guy who worked in paint and he had no idea what it was. Germans don’t use as many corrosives as we do in the US. I’ll take a look at amazon.de.


I have two coins I’m going to try to conserve. I’ll start a new thread for the other, but we will consider those the before photos for this one. I’m happy to receive tips and suggestions as I move through the process.

 

Excellent answers for the most part. In my experience, acetone and other organic solvents will only turn your coin pink if it was previously cleaned and recolored. You coin looks like it has already been cleaned and recolored, so don’t expect perfection. I won’t use Verdicare, but after you use acetone, I suggest a GENTLE brushing with light mineral oil, using a soft (not metal) bristle brush. Mineral oil is neutral, won’t harm the coin and will protect the surface from oxidation. It was the preservative in the old Care and Blue Ribbon products that everyone pays stupid money for these days. Just don’t brush too hard. A light touch is best.

 

I've found some xylol/xylene online that shows 98% purity. Is that good enough?