Ok, over a year ago, I got a lot of unsorted Judaean bronze coins. After sitting for a while, I've had some help in sorting them out, but behold, the green spots have appeared on almost half of them.
Is this bronze disease? If so, is that it for these coins with the green spots? They were under $2 each and very common Judaean coins.
Yes that's BD. Various advice is available on the
Forum board for reducing the impact of BD, but the consistent advice is to be very quick as it spreads fast. I like this website resource (although for advice I'd go to
Forum first)
http://www.collector-antiquities.com/89/I
had one coin which disintegrated before my eyes. When I photographed it, it looked like this (see pic below). Bits fell of it as I was taking the photo. When I handled it later the same day, more bits fell off. I warmed it at a very low temperature (just above 100 degrees) in an oven to drive out the water. It apparently was full of water / water-vapour because that caused the entire surface to crackle over, presumably due to the release of water vapour. I picked it up and rubbed it gently and both the surfaces just came off with the cleaning cloth, the coin disintegrated, leaving a thin core with a powdery coating. I threw the coin in the trash. This all happened the same day the photo was taken. As you can see, it did appear to be a nice coin. I suspect that no amount of correct BD treatment would have worked at that stage, the coin was no longer made of metal.
You don't want this to happen I guess.
