FORVM`s Classical Numismatics Discussion Board
Numismatic and History Discussion Forums => Coin Photography, Conservation and Storage => Topic started by: Vergilius on November 19, 2008, 12:36:07 pm
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I am not sure whether this coin has bronze disease or not, the photos is not that good, but you can see the green spots on the lower left at the obverse and at the top left at the reverse. It also has a small green spot like this on the edge, and the colour of is sharper green than on the photo, which makes me think of it is BD. On the other hand the condition for this coin has not changed for the worse during the two years I have owned the coin. The big question is if I should, with the risk of maybe destroying the patina, put it in Gringot #1 to be on the safe side or if I should assume that everything is OK and leave it as it is.
In advance, thank you for any replies!
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Hard tell,but I think you are o.k.
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Hi. I can't tell from the photos. Your description sounds a little worrisome, but I also would expect, if is bronze disease, within a 2 year period more of an invasion showing up, especially in those cuts in the upper left of the obverse. Sorry I could not be of more help.
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What is confusing for me about this coin, is the colour which is similar to other coins I´ve had with BD, but while matching BD in colour it seems to be harder (it does not go off with a toothpick) and as I said, it has not got any worse for two years. That makes me think that it might just be encrustions, but that also seems odd becouse of the very green colour which stands out from the rest of the patina.
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YOu'll just have to go trough all the BD threads but I'm sure I've read that those hard green boils are also
(or can also be) BD.
Andreas
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From the looks of the two pictures there are two spots that bother me. One on each side. If this was one of my coins, I would use a needle to carefully remove as much of the pale green as possible, then soak the coin. The dark green is malachite and should not be disturbed by GG #1, not should the dark copper oxide. The two spots, if they are BD , will show raw copper, but that cannot be escaped, in that case, a bit of Deller's would reduce the contrast and then leave the coin in the open, it will darken further.
If they are BD, action right noe will prevent damage to a good looking Follis.
Bruce
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Thank you for the help. Then I will soak it in GG #1 to be on the safe side. I really like this coin, and I now have an almost complete collection of the anonymous follis, so it is probably best not to take any risks with it :)
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If you carefully pick open the areas that I circled, then soak with sone scrubbing in those areas, the reat of the coin should not change. I would allow at least a week of soaking, scrub lightly daily, change the solution every two daus. I would not use less than 8 ounces to soak the coin in, the idea being to keep the concentration of chlorides from being able to build up in the solution, so the dissolution gradient is away from the coin. Besdies the carbonates tent to cause the bronze to darken depending on the alloy. I often fininsh with a soft brass brush on my battery powered dremel and the areas blend in without added toners.
Bruce