I put a clad Kennedy half in acetone to try and get a little patch of some unknown substance off. Forgot about it and came back a day or two later. Needless to say the acetone had long since evaporated and the entire coin was splotchy and discolored. Additional acetone baths did absolutely nothing as far as removing the new stains. *shrug*
Ancients get away with anything but newbies are highly restrictive so until I'm considered ancient no way am I going to use anything including acetone on my beloved coins!
Oh now chemistry. Acetone, a common solvent for inorganic and organic chemistry, acetic acid, if undiluted it’s known as glacial acetic acid and to make acetates of such element or chemical like calcium acetate, Ca2(C2H2O2), which is known to be flammable. So my question is why acetone and acetic acid are structurally, chemically, and sounding so similar to each other?
Give it another acetone bath, and then remove it from the acetone and immediately rinse it with distilled water. That will remove those splotches.
Are you really 12 years old? Acetone is a common solvent, but NOT for inorganic chemistry. Acetone That -OH that replaces the -CH3 of acetone makes a HUGE difference. Acetone boiling point 132.8 degrees F Acetic acid boiling point 244.2 degrees F Calcium acetate is not flammable. Interesting fact: Pure acetic acid is called glacial because it is solid at room temperature and "resembles" a glacier.
Because they're so closely related, they got similar names, back before names were systematic (constructed according to well-specified rules). "Acetic acid" got its name twice from the same root. Acetic comes from French acétique (vinegar-like), which in turn comes from Latin acetum (vinegar, originally vinum acetum, "sour wine". Acid comes from Latin acedus (sour, sharp, tart), which also shows up in the Latin phrase above. So, acetic acid sounds kind of silly and redundant, because that's exactly what it is. Acetone was first prepared in a lab from acetic acid, and got a pseudo-classical name that basically means "daughter (-one) of vinegar (acet-)". When chemists started discovering other compounds that were similar to acetone, they adopted ketone as the general name for the class. Acetone is the simplest ketone. There are innumerable others, and they're really important in biochemistry and flavor chemistry.
On this 100% question, acetone will never be 100% pure. Like alcohol, it is hydroscopic and will absorb water vapor right out of the air. This makes it VERY hard to get all the water out of it. So even though it says 100%, it won't quite be. you can figure it will really be 97 or 98% pure. The only way to guarantee a higher purity than what you can get in the hardware store is to buy reagent grade acetone (guaranteed 99.5+% pure) and that is going to cost you about $25 a pint plus shipping.
And even that will start absorbing water as soon as you pour it and get humid air into the bottle. Not much, and not quickly, if you keep the bottle tightly closed when you aren't actually pouring it. Or you can dry it. Dump some 3A molecular sieves into it, and it'll be plenty dry -- again, until you pour it into a container holding your coin. (Watch out for ceramic dust, too.) Really, unless you do all your work inside a glovebox filled with dry gas, you'll have some water in the acetone. It almost certainly doesn't matter. That small amount of water doesn't substantially interfere with the acetone's solvent properties, and the acetone takes it along when it evaporates.
Someone mentioned acetone is not good for copper. That may be true. I recall a copper coin that I left in acetone for a while (days). When I finally removed it and let it dry, it had a dark bluish tone to it. I never blamed it on the acetone but now I think I might have been wrong. More input on this, please.
Acetone evaporates very quickly and it's important to use a air tight container, preferably glass or other material that won't dissolve from the Acetone.
Chemistry is a subject more mystifying than coin collecting. I don't think acetone SHOULD do anything to copper, but I'm also sure that many people here are convinced that it does. Could be impurities in the acetone, in the copper or in the container...who knows.
If a person takes it out of acetone and then let it air dry, a color may well appear as the impurities the acetone removed attaches right back on the coins surfaces as a thin film of 'whatever' refracting the light as it can't carry the impurities away like it can water molecules. I would put any coin made of mint metals in it all day if it is in a normal conditions and not a high moisture,high heat ,high UV radiation lab experiment as the "one" people mention. They were working for a solvent company trying to show the product was better than acetone for cleaning copper tubing and fixtures before soldering. I could find no evidence it was peer reviewed beyond their publication. IMO, Jim
According to researchers at SUNY Stony Brook, when copper is exposed to acetone in the presence of water vapor and light, AND the acetone was allowed to completely evaporate, acetic acid will SLOWLY form (their words). The acetic acid then can react with the copper metal to form copper acetate. Copper(III) acetate is blue or bluish green. However, when the experiment was done under the same conditions in the dark, no acetic acid formed. So what does this mean for the average collector using acetone to remove PVC plasticizer residue from copper. To avoid forming copper acetate, this is what I do * Only soak for short periods of time. I do 15 min max. If you feel the need to soak longer, put the sealed container in a dark, cool place. Remember, the researchers said the reaction will not occur if there is no light * Don't let the acetone completely evaporate. If this happens to you, you need to start paying more attention to what you're doing. * Avoid using in humid conditions (although I would have no problems if using a short soak) * Use clean acetone. * After the initial soak, rinse quickly with fresh acetone. Remember, the junk that was once on your coin is now floating around in the solvent and can redeposit when you pull it out (or if you let it evaporate) * I like to rinse with Distilled water. Others have said this step is not needed, and I have no reason to dispute that. However, I feel better knowing that I've done everything I can to remove any remaining residue. * IMPORTANT: Don't play with chemicals if you aren't familiar with handling them. Acetone is flammible, evaporates quickly, will damage many countertops and plastic pipes, and can dry out your skin. You can get in real trouble very quickly if you don't know what your doing I don't disagree that others have had problems using acetone on copper, and based in this research, it could happen. But that research can also provide steps to minimize/eliminate those risks. That's why I feel using acetone on copper is not a problem. This is a summary of the article in a SUNY Stony Brook publication. https://www.stonybrook.edu/vescalab/research/research7.html @desertgem the full article appears to be published in a peer reviewed journal, but I don't have access to it. I also saw another article from the authors making similar conclusions regarding aluminum alloys containing approx 5% copper when cleaned with acetone and exposed to Cl ions. That research was sponsored by the Air Force
Here is the original article as in Electrochimica Acta Electrochimica Acta 46 (2001) 2337 – 2342Photochemical breakdown of acetone on copperSanjay V. Kagwade, Clive R. Clayton *, Devicharan Chidambaram1,Gary P. HaladaDepartment of Material Science and Engineering,State Uni6ersity of New York at Stony Brook,Stony Brook,NY11794-2275,USAReceived 3 August 2000; received in revised form 25 November 2000. I can download it with my college account, but maybe not otherwise. I don't debate that their result occurred under their conditions. They used 99.9985% 0.1mm copper foil and scrubbed it with 240 grit SiC paper, rinsed with acetone and put into 15ml of acetone in a small beaker and the beaker put into a water bath, then that beaker was covered by an inverted beaker over it so water could produce a high humidity environment. An Al Ka line with energy of 1486.6 eVand 400 W was used as ambient light.They allowed the acetone to evaporate during the 18 hour process. I do not, and probably no collector would feel that the above was normal for the purpose of removing organic material from metallic coins. Imo, results may vary Jim
