Our US coins can often be found with a SOFT, green deposit (usually in a recess of the design) that can be easily removed w/o a trace if caught early enough. Dark dirt deposits occur in the same places but these are rarely soft and using the method I outline below should not be done (you may scratch the coin) as they are removed in another way. ALL treatments such as this should be done under a stereo microscope or magnification that leaves both hands free. We use this method for tiny areas. Take a round toothpick and shave it down to a thin sharp point. Touch the residue to make sure it is soft and not a hard green corrosion spot. If it is soft, gently push the green off using tiny forward motions with very little pressure. Note: While acetone on a Q-tip will also work, the acetone will take the "skin" off the coin and it may on longer look original.
Verdigris is the hard deposit I take it. The chemical process that eats our copper coins..... So what I am gleaning from this is that all green deposits are not necessarily verdigris then?
Randy Abercrombie, posted: "Verdigris is the hard deposit I take it. The chemical process that eats our copper coins..... So what I am gleaning from this is that all green deposits are not necessarily verdigris then?" From my reading "Verdigris" is the chemical reaction or the result of various chemical reactions so depending on how it is used, that word can be applied to virtually anything dealing with green colors, copper, or copper alloys. So, I guess this deposit qualifies to be called "verdigris." Right or wrong, I call hard green deposits corrosion; however hard green corrosion (patina) is desirable on some coins - especially ancients.
Insider,You might try a shaved down to a point bamboo skewer stick . Bamboo has micro-tiny xylem ( for water transport) through out it, so any solution you may use will be drawn up into the point and be dispensed like an old fashion "dip and write" ink pen. More flexible than toothpicks. All done only under a stereo scope like you say. IMO, Jim
Interesting...was unfamiliar with the term "Verdigris" (except as verde is Spanish for green, as for a flavorful "verde" sauce)...but have been using the sharp toothpick method for years in removing soft debris from coins or testing whether soft or hard. Alas, have never had/used a stereo scope, but appreciate the cautionary advice.
No, it isn't. Verdigris is the result of copper corroding - just as rust is the result of iron or steel corroding. Verdigris is what the copper is turned into by the chemical process of corrosion. In and of itself, verdigris is harmless, it does not and cannot do a damn thing to coins. You could leave it there for a thousand years and it won't do anything to coins. And no it does not and cannot cause more corrosion. The only reason there is to remove it is because it is unsightly. Of course once you do remove it the damage to the coin, (that is underneath the verdigris), that was done by the corrosion will be visible. On all metals, corrosion is caused by two things - moisture and the air.
Thanks for the info. Glad to know verdigris does not actually harm the coin, just creates "non-beauty spots". A few of my copper coins have small amounts of verdigris. To me, trying to remove it and possibly damaging the coins is not worth it.
Great thread. I also use a scope for work like this. I have learned to not trust everything the camera shows. Sometimes the camera makes things look green but in hand or under the scope they are just a dark spot that should not be messed with.
Well, once it becomes available again and according to its maker it's going to soon, Verdi-Care will remove light verdigris. And it will do it safely and not harm the coin. And yes I have tested it myself.
Read this again. "Verdigris is the result of copper corroding - " if that ain't damage, I don't know what would be!
You're right. Any coin that has verdigris on it has undeniably been damaged - because verdigris cannot exist unless and until after damage has already been done to the coin - by corrosion. But, and this is the point that whopper64 was making, at the same time it must also be understood that additional damage can be done to the coin by trying to remove verdigris if you do not do it properly ! It is also important to understand that verdigris is not found on only copper coins. Verdigris is also commonly found on silver and gold coins as well. Including those that are .900 fine and higher. And for those reading this, if there are still some who don't get it, think of verdigris like being like sawdust. Sawdust is produced when wood is cut or sanded. So sawdust is the result of cutting and or sanding wood. It is the cutting and or sanding that does the damage, not the sawdust. edit - added the word "don't" above. Mind works faster than the fingers sometimes
Well said, the only thing I would add is that the coins have to contain some copper if they are going to have verdigris.
