I recently was given some old Lincolns (1910 through 1920) and some Buffalo's that have some hardened green stuff attached to the coins. Could this be PVC? I'm not a fan of cleaning coins but in this case I think a cleaning/restoration is, with out a doubt, in order. What is the best way to remove the substance which does the least damage to the coin?
It may be possible that it is PVC which you can use acetone to remove it without any worries. Do experiment on copper first before trying it on the whole batch. I am somewhat doubting that it's PVC. Instead I think the green substance on your coin is verdigris, which is copper chloride or copper acetate (can't remember which) is impossible to remove without damage. You might want to post some pictures beforehand so that it's easier for the other members to see what kind of damage you got there.
I don't have a digital camera so I can't post any pictures. But your description seems to be in line with what is on the coins. I'll wait for more replies before I try anything. Thanks for the reply............
i have heard that a long soak in olive oil will help, never tried it so experiment on something with high mintage and little value first. grizz
Biox is a cleaning solution that will remove verdigris. It can be purchased - HERE That being said, no I have never used the stuff myself. I have no idea what it will make the coin look like once it has been cleaned. Experimentation would be in order. Either way, it is a given that verdigris will continue to damage the coin until it is removed. So make our own choice about which outcome could be worse.
Though olive oil and WD-40 will remove some of the verdigris it will not remove all of it. And then you also have a coin that is coated with oil if you use either of these methods and then the oil must be removed. And since water and oil do not mix, water will not remove the oil. That means you will then have to use yet another a chemical to remove the oil. This is largely the problem with using home remedies to clean coins - it only works in half measures and you still have to clean them yet again doing even more damage. It's a personal choice, but one that should be considered.
When using on coins, acetone will clean up WD-40 and Olive Oil I've found. There are many options one can use to tackle the verdigris problem, and I've tried many of them http://www.provincial-romans.com/cleaning_romans.htm To put in perspective, WD-40 is used regularly in cleaning and maintaining modern and ancient firearms. Take Care Ben
Thanks for the replies. I'm gonna try the WD-40. Again these are not valuable Lincolns, about $5 to $10+ a coin F to VF. But with the "green stuf", maybe $0.10 a coin. So I'll try one coin first and see what happens. However, two questions remain: How long should the coin be submerged in WD-40? I've heard of people soaking coins in oil for weeks before the coin is restored (although technically cleaned). What should I use to remove the substance (fingers, toothbrush, etc.)?
Actually that "weeks" should be months. And it doesn't always work even after months. That's just it, you shouldn't use anything. Using your fingers, a cloth, a toothbrush or any other brush - all these things do is to scratch up the surface of the coin. What you should do is use a chemical that will remove the verdigris all by itself, without you having to touch the coin at all.
What you have is NOT PVC, NOT Verdigris, Not anything to do with exposure to an Acetate. However, it is possible if your coins were exposed to Vinegar if could be a sort of Acetate Cu ( C2H3O2)2-H2O. The common misconception of PVC contamination is a what is normally called an "Old Wives Tale" This is when people just say something they've heard and repeat it over and over and over. However if your coins were exposed to PVC at a temperature of over 200 degrees, that is also possible. Since your coins are Copper or contain Copper and have been exposed to normal air, moisture and Carbon Dioxide, they are just slowly doing what all Copper compounds do. OXIDIZE. This is normal and can be seen where ever Copper is utilized. If you have any Copper piping you will also see it there. Brass and Bronze are Copper compounds and will also eventually turn Greenish. The process is Cu + O = CuO2. Once this browniing occures it is now suseptable to being attacked by moisture ( H OH ) and Carbpm Dioxide ( CO2 ) thus forming Copper Carbonate [ CuCO3-Cu ( OH )2] a greenish substance on Copper. Occationally there is a further reaction if the air in your area is contaminated with Sulfur Oxides ( SO ) or ( SO2 ) from Coal Burning organizations. Such substances in the air compbine with moisture to produce what is known as Acid Rain. The final substance on such coins is now Copper Sulfate CuSO4. There are numerous methods to remove all such substances such as Olive Oils, WD-40, Acetone and even some say Tamato Juices. Regardless, remember the removal of such green substances will also remove some of the coins metal. Regardless not that most, not all, of the substances refered to contain an ACID. This will further attack your coins. Then a rince in distilled water will be required. The safest way to remove this green substance and maintain chemical neutrality is Baking soda/distilled water paste. This will neutralize any further, at least temporary, chemical reactions. ONE MORE TIME. Removal will be considered cleaning and the end results will be a cleaned coin.
Sorry Carl, but you're just plain wrong on that count - chemist or not. PVC contamination is a very real occurrence. And it doesn't require any high temperatures or anything else but time. PVC coin flips will break down over time due to the plasticizer used in them. This then turns into an oily film which is deposited on the coins and it will literally eat the coin's surface away. And whether you want to believe it or not, verdigris can and will form on copper coins under the right conditions. Verdigris
