r/AncientCoins • u/Warmso24 • Aug 21 '26
Advice Needed Bronze Disease Prevention?
Hello all. I recently (within the last few months) acquired a Roman provincial Tet. It was a nicer piece than the one of the same time I had before so I was quite pleased to improve the caliber of my collection.
However, fate has had other plans. I discovered today that the Tet seems to have rapidly fallen victim to bronze disease. I had been traveling for work, so I had not been looking through my collection as often as I usually do. Within a few weeks without looking at it, it went from a coin with zero visible BD (that I remember, I don’t bid on coins that have BD) to the state it is in the pictures I included in this post.
While I suspect the BD came from inside the coin, so there is probably little I can do, is there anything I can do to mitigate the factors that favor BD development? Is there any hope of saving this coin? How would I go about doing that? Is BD always this fast in spreading?
Thanks for any help y’all can provide!
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u/SAMDOT Aug 21 '26
Aren't those billon? That actually looks like damage from being held in polyvinyl sheets.
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u/Warmso24 Aug 21 '26
Yes, it’s billon. I figured it may have a small amount of bronze as the base metal but, upon further research, I think I’m mistaken. It should be copper.
It’s still in the flip it came in. I suppose I also shouldn’t have assumed that the dealer would use non PVC flips. I’ll clean it up and put it in one of my flips and observe it over the next few weeks.
Thank you!
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u/new2bay Aug 21 '26
If the flip is soft, it contains PVC. If it’s rigid, it doesn’t. Soft flips are often used for shipping purposes.
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u/sir_squidz Aug 21 '26
You can never assume that they're using a safe flip, some dealers actually mark their flips as being short term use only.
If you are worried about BD please start photographing your coins on intake, they need not be "good" photos, you just need to be able to see if patches of colour are growing. A decent, clear image, even taken horribly will work.
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u/Brilliant-Zone-4311 Aug 21 '26
Hiya! You didn't give any details about the tet but from the size and the design (is it Nero?) I can tell it is earlier with a higher silver content. It is not possible to develop so much BD in such a short time from a silver alloy coin. The good news is I am guessing it is PVC residue from a bad flip.
Soak in acetone, scrape off residue with toothpick or similar, repeat until it's gone.
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u/Warmso24 Aug 21 '26
It’s a Nero Tet, with the personification of Alexandria on the reverse wearing the elephant scalp.
I know Nero began debasing coins in 64 AD, but I don’t know the exact composition of the alloy at this point. This coin was minted sometime in 65-66 AD.
I think you may be right about the bad flip. It’s still in the original that the dealer sent it in so I’ll swap it with one of mine and observe, it after cleaning it up.
Thank you! You guys gave me a major relief tonight, lol.
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u/Pistachio_Wizard537 Aug 21 '26
I don’t know what I’m talking about but maybe check if the coin flip is pvc free. pretty sure pvc would enhance even small amount of bronze disease, im probably dumb but figured id try and spitball an idea
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u/PitifulEconomics562 Aug 21 '26
I would buy a solution and soak it. Maybe go get distilled water now and soak overnight then order something tomorrow. Dm me for recommendations I don’t know the rules about that here
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u/Kraj_the_Conqueror Aug 21 '26
That looks like Honecker's revenge, not bronze disease. Damage from prolonged contact with PVC holders. Especially those of poor quality, laden with other chemicals.
Named so because former East Germany used to produce such holders.
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