I've been fascinated with verdigris ever since I began collecting. I started experimenting with worthless LCs in an attempt to remove the crusty nuisance and ended up with a process that I believe to be harmless to copper cents. (Not to be tried on zincolns.) Anyway, I found this affected 1967 and here are my results.
The process: Soak coin in olive oil. (This will help to retain the coin's patina.) Wrap soaked coin in paper towel. Tape closed with cello (scotch) tape. Boil for 15 minutes. (Verdigris decomposes at about 440f, but will break down enough in boiling water... about 215f-ish... depending on where you are relative to sea level, believe it or not.) Remove from boiling water and immediately agitate affected area with a baby's soft toothbrush by gently swirling in very small, concentrated circles. (OK. Let me have it. LOL) Then, pat dry... and then air dry... and then, apply verdi-care.
Now, you don't really have to go to great lengths to educate me as to how frowned upon coin cleaning (There. I said it. Coin cleaning. <smile>) is in our hobby, but I just happen to be of the opinion that I'd rather own the "after" as opposed to the "before".
I would like to see a full shot of the coin and the reverse, it looks good to me and i myself have experimented with ways of straightening out coins, better then saying cleaning lol. the only reason i want to see full shots is to see how the color looks over all.
If this works for you George, then go for it. The only drawback I see is the amount of time it would take to do this.
I think no more than 30 minutes. Knowing what I know, I would not suggest doing this on anything super valuable, but if I had a crusty 60 SD that I wanted to sell on eBay, I think it would be worth the time.
FYI - I took the soft baby's toothbrush (dry) and attempted to damage (by aggressively beating and applying great pressure to) a near perfect 2013 LC... and under the scope, I could see micro scratches as a result. (Not sure what the property differences are between the plating of a zincoln and a true copper LC are, but gently and softly swirling this '67 could be no worse than what it had surely been subjected to in the countless jeans pockets and bank bags it had likely seen in its day.)
"Cleaning" a coin and removing surface contaminants are two completely different things. What is going on here is ONLY "cleaning" (numismatic definition) if metal molecules are noticeably moved (i.e. hairline scratches in the coin). If you can find a way to scrub a coin and not move - or remove - one bit of the metal of which the coin is made - then you are effective 'conserving' the coin, not 'cleaning' it (by numismatic definition).
By what I can see, I would say that the 1967 cent pictured in this thread is effectively 'conserved' - not 'cleaned'.
The one point I would raise is the same as Bob - it takes a long time.
Another thing is that while the coin doesn't sit in the olive oil long, and it appears by the description of the method that it is boiled off a short time later, I doubt this would make a LOT of difference, but consider the following:
Olive oil is a plant-based oil, which means it can go rancid and it can rot, which will effect environmental damage on coins. It is also somewhat expensive as compared to the more preferred oil for coins.
Mineral oil is mineral based and does not go rancid and does not rot. It will not place contaminants on coins, and is very inexpensive. It also effectively does the same thing to coins as olive oil.
I always recommend staying away from olive oil on coins for these reasons.
Charles D. Daughtrey, NLG, Author, "Looking Through Lincoln Cents"
[URL="http://www.coppercoins.com/"]http://www.coppercoins.com[/URL]
Mineral oil is mineral based and does not go rancid and does not rot. It will not place contaminants on coins, and is very inexpensive. It also effectively does the same thing to coins as olive oil.
I always recommend staying away from olive oil on coins for these reasons.
Thanks again, Charles. Good info, as always. (Can my GF use mineral oil in stir-fry? )
Well, I guess I would say first I have no problem with what you did...but I have a problem with what you call "verdigris". My definition of Verdigris is a GREEN corrosive salt like affect on copper that actually eats into the metal WHILE creating a chemical crust around said spot. What your pictures look like is just normal circulation crud in the devices which with a long soak in Acetone will remove. The problem with Verdigris is that it eats away metal...depending on the length of time and surface area covered, the green corrosion can be removed, but now you have a hole to deal with.
Well, I guess I would say first I have no problem with what you did...but I have a problem with what you call "verdigris". My definition of Verdigris is a GREEN corrosive salt like affect on copper that actually eats into the metal WHILE creating a chemical crust around said spot. What your pictures look like is just normal circulation crud in the devices which with a long soak in Acetone will remove. The problem with Verdigris is that it eats away metal...depending on the length of time and surface area covered, the green corrosion can be removed, but now you have a hole to deal with.
WS
Could very well be... I figured there was likely some verdigris present beneath the crud, but had no real basis for the assumption. Thanks for chiming in and for the advice. Verdigris is indeed a corrosive and should be removed from anything that you care about. (Shield cents..? Why bother? )
Actually, an interesting process. The olive oil is insoluble in water and by wrapping the coin in a paper towel, you probably kept most of on the coin during the boil. I agree with Chuck, I hate olive oil on coins, a better choice would have been mineral oil since it was really just a medium in which to disperse the heated gunk and to protect the surface. Olive oil contains a variety of organic acids and compounds that will eat at the patina.
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