PVC Damage Or Bronze Disease? - Coin Community Forum

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Author	Replies: 4 / Views: 1,511
Pavlos New Member Netherlands 6 Posts	Posted 08/23/2018 07:15 am Hello, I got this ptolemy coin for a couple pounds, I liked the coin and I was like, there is nothing to loose for so cheap. When I first saw the green spot I thought it was PVC damage because the seller literately handed the coin to me in a PVC slab. I got the coin now around 20min in acetone, the white stuff seems to be gone but the green spot is still there. Before picture of the coin: Now I am actually wondering if this is PVC damage or is it maybe bronze disease? I didn't think of bronze disease because I see nothing flacking off.I need advice how to remove this green spot. Thank you. Report this Post to the Staff

sel_69l Bedrock of the Community Australia 21788 Posts	Posted 08/23/2018 07:29 am Bronze disease, unfortunately. It needs to be passivated. There many sites on Google on how to do this. PVC plasticiser will gas out over a long period of time, but the plasticizer oils are organic, they affect all coins with a different chemistry. Blackening of copper and bronze coins is the most common result, which is also permanent. The bottom line is do not store your coins in soft PVC album pages. Report this Post to the Staff
echizento Moderator United States 23731 Posts	Posted 08/23/2018 2:39 pm to the community It does appear to be the start of bronze disease. This might help: http://www.crescentcitycoinclub.org...0Disease.pdf http://www.classicalcoins.com/bronze_disease.html Report this Post to the Staff
Pavlos New Member Netherlands 6 Posts	Posted 09/05/2018 12:05 pm It has been some days now and I put the coin in distilled water with 2% baking soda. The green spot is much less, I will let it soak a little more because it is not removed all the way. However, something really disturbing happened, at the bottom of the coin near the feet of the eagle a black spot has formed. The black spot doesn't seem to go away with a brush or a toothpick. When I search on google for a black spot on bronze coins, I get results about "carbon spots". I doubt however that a carbon spot has formed in the course of a week in distilled water with baking soda. Does anyone know what this might be? It is really weird this suddenly happened, it ruined the anesthetic of the coin quite much. I will try to post a picture later on. Thank you. Report this Post to the Staff
Ben Pillar of the Community United Kingdom 4208 Posts	Posted 09/14/2018 09:41 am Ptolemys often have big green encrustations; I've never been able to get one off the whole way. If you have success, please do update. The black spot looks like it might be present but faint in the pictures. A lot of cleaning procedures can darken surfaces; not much to be done about it. You can darken the rest of the coin, which takes a long time, but is simple; just leave it in some olive oil. Check frequently (~fortnightly), especially if it has had bronze disease. Report this Post to the Staff
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