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 Replies: 12 / Views: 2,378 |
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Pillar of the Community
United States
3546 Posts |
Hi, The attached photos are from a coin that I found in a 70 lb. lot of foreign coins that I purchased for $ 240.00. Anyway, the $ value of this coin appears to be excellent but might even better if I could find an effective way to remove this black gunk without damaging the coin. I have already tried acetone without any success whatsoever. I fear using olive oil since that last time I soaked some copper coins in it for two + months the coins began to show pitting. The pits began to initially manifest themselves as a result of the acids that subsequently formed even though they were not initially present. Two objectives ideally need to be accomplished here in this post: 1) determining the most effective and least damaging method(s) and combination(s) of chemicals to bring the surface of this coin as close to its original position as possible and 2) assigning a grade to this coin both pre-cleaning and post-cleaning. I am unsure if I personally should copy this thread to another area of the CC for the grading portion or should just wait for the cleaning suggestions first. Please advise. Thanks, mdpmedia   |
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Pillar of the Community
 United States
3546 Posts |
Any ideas out there circulating from the cleaning gurus?
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Bedrock of the Community
United States
17884 Posts |
I think you can forget it. I don't think you'll be able to remove then without further damaging the coin.
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Pillar of the Community
United States
3546 Posts |
How does one determine what this residue is actually composed of?
I ideally would at least like to know what I am dealing with.
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Bedrock of the Community
United States
19935 Posts |
Olive oil contains organic acids and is natually acidic. Given enough time, the acids will eat into the surface. Oil is old school, it is primarily used because collectors have propagated the method for decades. Unfortunately, for every coin it saved, another 100 were ruined by it. It is very inconsisent and has a slew of problems....leave it for the salad and not coins.
The dark toning spots will be impossible to remove without damaging the surfaces. Personally, I like the dark toning spots, they give the coin nice character. I wouldn't worry about them....however, I would worry about the verdigris. VERDI-CARE would be very effective at removing the verdigris and other residue traces.
Lincoln Cent Lover!VERDI-CARE™ INVENTOR https://verdi.care/
Edited by BadThad
07/19/2011 11:03 pm
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Rest in Peace
United States
1729 Posts |
Actually, these spots ARE part of the surface -- you proved that when acetone failed to remove them. Remove them, and you've damaged the coin.
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Bedrock of the Community
United States
20753 Posts |
BadThad sort of said it all. Items, such as Olive Oils and most man made products are inconsistant in their composition. And in most instances this is done purposely so as not to easily be copied by competitors. Never try something that people say will work from such products that may be completely different than the ones they used.
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Pillar of the Community
United States
619 Posts |
There is one thing you can do. I wouldn't try it on good coins, but it seems to work on my junk silver; I don't know about copper. Mix hot water with baking soda. Lay a piece of aluminum foil in the bottom, maybe add a little salt. Let it soak for a while, and make sure not to scratch it. Then, rinse it with clean water. It will take all the tarnish(and toning!) from silver.
Edited by CPC24
07/22/2011 8:36 pm
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Pillar of the Community
United States
3402 Posts |
I've used olive oil (extra virgin) on my coppers with good results. First I try acetone/xylene then alcohol. You don't just let it sit in an O/O bath for two months.I use q-tips and a light touch. Rinse in distilled water and try again. I usually do this on a daily or 2-3 day basis.
To get a more pleasant toning you might try to keep the coin next to your body, specifically in a mid region area. I usually get a nice brown overall appearence.
KK
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Pillar of the Community
United States
3402 Posts |
Oops I forgot.
70 lbs. for $240. That's a great price. Anymore available?
KK
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Pillar of the Community
United States
3546 Posts |
KK,
That $ 240 price for 70 lbs. of misc. foreign coins happened to occur at a mid week auction that had very people attending and only 3 - 4 coin buyers.
I really think I lucked out on these coins being that the dates range from the 1830s to the 1960s.
As with any auction, however, I could have also easily purchased 70 lbs of picked-through foreign coins ranging from 1950 to the present having little or negligible value.
Once again luck was on my side since the auctioneer did not allow me to pick through all of these coins before I purchased them; it was a one-money-for-all purchase scenario...
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Pillar of the Community
Australia
560 Posts |
Arn't these the early stages of patina formation, cauused by oxidation of the melal?
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Bedrock of the Community
Australia
21786 Posts |
CPC24:
I have a nice 1902 Indian Rupee in AU with rather distressing and very obvious black silver sulphide spotting on it. Other than that, the coin has no toning, perhaps because someone has attempted to clean it in the past.
I bought the coin for bullion value only, and as it is, I think that is really all it is worth.
I am wondering if your method would remove those awful spots?
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Replies: 12 / Views: 2,378 |
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Posted 07/19/2011 1:53 pm
