Is using pure acetone considered"cleaning"?

I had a friend show me a large cent he got from his grandfather. The thing was completely green. I could tell there was a coin underneath, but hardly much else. Took me a week, a gallon of acetone, and a case of q-tips..... but by the end, that thing was a gorgeous piece of copper and you couldn't tell anything had ever happened to it.

(I may be exagerrating slightly for effect.....)

Here's the actual story: https://www.ngccoin.com/boards/topic/146159-pvc-and-acetone-a-detailed-step-by-step-pictorial-guide/

 

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Yore........

 

I'm lost for words.......

 

Just read the actual story. I like his detailed
account of the procedure. Thanks for sharing.

 

I'm a fan of using acetone on copper. It can remove impurities that are masking the true color below it. I have seen a few change color after an acetone bath.

Folks have been treating coins with all kinds of stuff for many years. Just think of all the ways people try to darken copper. Some don't tone the copper they just lay on the surface of the coin.

 

Using acetone to remove crud is cleaning. To be clear, it is chemical cleaning which doesn't harm the surface of the coin, but it is cleaning since you are removing surface dirt and contaminants from the underlying metal. It is definitely not mechanical cleaning (like with a brass wire brush which I use on crusty asian cast coins).

 

It's safe to use. This is not an opinion. It's a fact. The effects are well known.

Some caveats. Special coins with mint-applied coatings, enamel, colorization, inset stones or other pieces, or other coatings like coins that glow in the dark, you probably do not want to use acetone on.

 

My only theory on this is that the crud itself has trapped contaminants, and dissolving the crud frees the contaminants to settle on the surface of the coin. But since you a swirling a coin around in the acetone, even this seems far-fetched. It's easier to believe there are trapped contaminants held next to the coins surface by the crud, and that cleaning away the crud reveals the results of that. But, I agree that the assertion of a direct reaction between acetone and the copper is very hard to believe.

 

I think this is the article. But the summary leaves out some important factors. You can ask for the complete article. It was financed by a company that makes chemical solutions that clean copper pipes for soldering. It tended to negate the use of acetone to clean the pipes ( easiest) and promote their solution. I have listed that experiment before, but can't find it at the moment. Doug and I have posted before on this , and it is my belief that copper coins would never be exposed to the experimental conditions that the experiment was done. But it is normal for people in science to disagree, and Doug has used and been around these chemicals also as have I.


https://www.researchgate.net/publication/229301116_Photochemical_breakdown_of_acetone_on_copper

Jim

 

I agree with your comments. Generally, I would conclude that the user left some residual organic material or didn't rinse the residue off the coin. However, Doug is experienced in this area, which makes it all the more interesting. I am still waiting for the science to explain what is happening.

Here is a more detailed abstract of the Stony Brook paper, along with the abstract to a follow up paper (which is not applicable to numismatics). Once again, I can't see how the acetone reacts with copper during the normal usage in removing organic substances from coins (shorter soaks, thorough rinsing, not letting the acetone evaporate after prolonged soaks).

https://www.stonybrook.edu/vescalab/research/research7.html

http://jes.ecsdl.org/content/147/11/4125.abstract

 

Ok, those are some promising links to some abstracts which may prove informative, but the abstracts alone don't help anyone.

Have any of you actually read the whole paper? Do any of you have access to the full text instead of just the abstract? If so, please PM me and I'll give you my email address so you can send it to me.

 

I don't seem to be able to find the threads you mention. Could you provide links? Or photographs? Or names of people we can contact who may have those? If this is such a common occurrence, maybe you can show us auction listings which demonstrate the look you've seen?

I just need some sort of objective evidence, and I haven't seen any.

 

Here is the best current source for it I can find. You might have connections with one of the educational and commercial groups that can get free download access ( I clicked PDF and it led me to the sign in and allowed a search of colleges, etc.

https://www.sciencedirect.com/science/article/pii/S0013468601003590

 

I've been thinking about getting some pure acetone and trying it on an old British copper half penny. It is so dark that the details can only be seen under a very bright light. Then again, my eyesight is terrible. It is from 1855. I'm not looking to make it look like new; just make it easier for me to see some details. Is it worth a try?

 

Acetone is not going to help you. It's not going to brighten the coin.

 

If it is that dark, LDhair is right. Most likely there are almost no details as it sounds corroded. A strong acid such as in a silver dip will take it to Yellow almost, but you can satisfy your curiosity. I don't know its value as I do not collect in that area. Jim