Help! PVC Damage To Silver Denarii and Shekel! Acetone? Alcohol?

[DitrasetMan]

Friends,

I forgot about a few silver denarii and one silver shekel that I put in PVC holders 30 years ago! They are green as can be and have a greasy feel to them. Yikes!

What is the current recommendation for removing PVC damage these days? I have heard that acetone is the usual course but I have heard other recommendations also.

Should I:

(1) Let them sit in a bath of acetone for 15 minutes; or
(2) Let them sit in a bath of rubbing alcohol for 15 minutes; or
(3) Let them sit in a bath of soap and water for 15 minutes;

And, in any of the above situations, should I use a Q-tip to "whirl around" in areas where the green doesn't come off?

Lastly, in one of the silver coins, black (very very dark) spots appeared on one side of the coin instead of the usual green. Could PVC cause that as well?

Thanks!

[David Atherton]

Soak them acetone for a bit, then gently rub off the green goo. You might have to do this several times.

[DitrasetMan]

Soak them acetone for a bit, then gently rub off the green goo. You might have to do this several times.

Thank you for replying. How long is "a bit"? And what would you use to rub and how hard can I rub?

Once the green is gone, is there any concern of it coming back if I put it in a Safe-T-Flip?

[David Atherton]

Thank you for replying. How long is "a bit"? And what would you use to rub and how hard can I rub?

Once the green is gone, is there any concern of it coming back if I put it in a Safe-T-Flip?

Depending on how thickly the goo covers the coin. 3-5 minutes would be a safe starting point.

Your coins should be fine once they are stored in non PVC flips.

[DitrasetMan]

Thank you for replying. How long is "a bit"? And what would you use to rub and how hard can I rub?

Once the green is gone, is there any concern of it coming back if I put it in a Safe-T-Flip?

Depending on how thickly the goo covers the coin. 3-5 minutes would be a safe starting point.

Your coins should be fine once they are stored in non PVC flips.

Is there anything else to this? Should I use a q-tip to remove excess residue? I also heard that I could setup three trays filled with acetone and dip the coins in each tray for a few seconds (so each tray is gradually less filled with residue than the preceding tray). That is certainly less than 3-5 minutes. Thoughts?

Also, what do you think the dark black spots could be?

[bpmurphy]

Acetone won't hurt a silver coin. Use in a well ventilated area. You probably won't have to rub it. If it's just PVC residue it will probably all come off in a minute or two with some gentle swirling of your bowl. You won't need a lot either, just enough to cover the coin.

Barry Murphy

[DitrasetMan]

Acetone won't hurt a silver coin. Use in a well ventilated area. You probably won't have to rub it. If it's just PVC residue it will probably all come off in a minute or two with some gentle swirling of your bowl. You won't need a lot either, just enough to cover the coin.

Barry Murphy

Got it.

But what about an area of the coin where the residue does not come off? Q-tip?

Is the 3-5 minutes single dip method the standard practice, or the multi-tray dipping method?

Do I need to dip it in water or denatured alcohol when I am finished to get rid of the acetone?

[bpmurphy]

Honestly you're making a very simple process way too complicated. The acetone will evaporate in under a minute once you remove the coin from the acetone. If you want, rinse the coin in water but it's not necessary. Any residue not removed probably isn't pvc residue. I've removed pvc residue so heavy the you could barely identify the coin.

Acetone will not hurt a coin, it's non-reactive with metals.  Even if you did something "wrong" which I can't imagine how you could, it won't hurt the coin.

Barry Murphy

[bpmurphy]

Jusr read your previous comment again. Not sure what type of tray you plan on using but if it's plastic be careful because acetone will dissolve some plastics. Just use a glass bowl, put all your coins in the same bowl, cover with acetone, swirl, remove. 20 coins will take you longer to remove the coins from the flips then removing the pvc from the coins.

Barry Murphy

[DitrasetMan]

Another question.

For my bronze coins that were in PVC flips and also have green stuff on them, should I use the same acetone process?

(For some of the coins I am sure it is bronze disease, but others I am sure it is the PVC)

[bpmurphy]

Acetone won't hurt copper either. You do run the risk though that if someone has added various epoxies or fake patinas that these could be dissolved in acetone.

Barry Murphy

[DitrasetMan]

Acetone won't hurt copper either. You do run the risk though that if someone has added various epoxies or fake patinas that these could be dissolved in acetone.

Barry Murphy

I assume that since it won't hurt copper, it won't hurt bronze.

[Andrew McCabe]

Acetone won't hurt copper either. You do run the risk though that if someone has added various epoxies or fake patinas that these could be dissolved in acetone.

Barry Murphy

I assume that since it won't hurt copper, it won't hurt bronze.

I wouldn't automatically assume that.

Bronze contains many other metals than copper, especially tin (in ancient times) and zinc (more usually in modern times) but also iron - which acetone can react with in the presence of water - and also some carbon and other organic compounds which acetone can dissolve and which may be especially prevalent in the surface oxidation (i.e. patina) layers. So it's true that acetone doesn't react with copper but that's not a guarantee that your bronze coin will look unchanged after an acetone dip. You want the coin to look changed (that's why you are dipping it in acetone) but results are not necessarily guaranteed. NB this post just reflects knowledge of chemistry. I've no views one way or another whether or not it's advisable to use acetone to clean bronzes; my only point is that non-reactivity cannot be guaranteed.

[DitrasetMan]

Acetone won't hurt copper either. You do run the risk though that if someone has added various epoxies or fake patinas that these could be dissolved in acetone.

Barry Murphy

I assume that since it won't hurt copper, it won't hurt bronze.

I wouldn't automatically assume that.

Bronze contains many other metals than copper, especially tin (in ancient times) and zinc (more usually in modern times) but also iron - which acetone can react with in the presence of water - and also some carbon and other organic compounds which acetone can dissolve and which may be especially prevalent in the surface oxidation (i.e. patina) layers. So it's true that acetone doesn't react with copper but that's not a guarantee that your bronze coin will look unchanged after an acetone dip. You want the coin to look changed (that's why you are dipping it in acetone) but results are not necessarily guaranteed. NB this post just reflects knowledge of chemistry. I've no views one way or another whether or not it's advisable to use acetone to clean bronzes; my only point is that non-reactivity cannot be guaranteed.

Thank you for your post. Great points. I guess there is no concern with the silver, but with the bronze coins it may affect the patina layers. I guess the question becomes is dipping the bronze and potentially affecting the patina the lesser evil versus letting the PVC stay on the coin.

Any other special things I should do with a bronze coin during the dipping process to try and not affect the patina?

[Andrew McCabe]

Thank you for your post. Great points. I guess there is no concern with the silver, but with the bronze coins it may affect the patina layers. I guess the question becomes is dipping the bronze and potentially affecting the patina the lesser evil versus letting the PVC stay on the coin.

Any other special things I should do with a bronze coin during the dipping process to try and not affect the patina?

I know nothing about cleaning coins, which involves questions of technique, artistry and value, as well as chemistry, so I've no answer to these questions. When I need coins cleaned, I ask others to do it for me. I do have views on when coins should be left well alone from a numismatic and commercial value perspective (since I know the market for the high-end bronzes I collect very well), but in the event that I feel something does need cleaning, I pass it to someone else. So, no answers to the above.

My comments on bronze reactivity were purely from a chemistry perspective, and only then on the logic that other metals and organic compounds within bronze means that non-reactivity with copper doesn't necessarily equate to non-reactivity with bronze.

[improbus]

I've been investigating this recently online, and the impression I had was that acetone wouldn't negatively affect bronze coins. I'm going to experiment on some low end ones in the near future to see how it works.

I knew about pvc flips, and I thought I was buying safe ones, but now I know better. Mine certainly aren't as affected to the same extent. My silver ones don't seem too bad.

I was thinking about just using paper envelopes from now on, but I'm not sure if there are issues with them.

[bpmurphy]

I've cleaned PVC off thousands of bronzes using acetone with no negative effects. Never left one in for more than a few minutes. Maybe if you left it in for a long long time there might be an issue b

Barry Murphy

[areich]

It has been said several times and it's correct. Don't breathe it in and avoid getting too much on your skin and you and your coins will be fine. Even if you do, it won't seriously harm you.

[DitrasetMan]

So, the PVC green goo around the edge of the denarii came off with the acetone and light rubbing with a microfiber cloth. However, the green PVC goo on the shekel will not come off! It had the worst PVC damage of all the coins. The green is encrusted on many spots immediately next to the raised features of the coin. I noticed the acetone removed much of the green on the edge (like the denarii) but not the green encrusted spots all over the obverse (oddly, the reverse is pretty much ok). I dipped it 4 times (the longest time was about 7 minutes) and I even used a soft toothbrush (light brushing and swirling motions) to try and "flick" out the green PVC. Nothing would budge! By the way, this shekel has been in a PVC flip for over 30 years.

Help!

[Jay GT4]

Pictures?

[DitrasetMan]

Here is the photo of the green 30 year old PVC encrustation that will not come off this tetradram. It was dipped 4 times (the longest time was about 7 minutes) and I even used a soft toothbrush (light brushing and swirling motions) to try and "flick" out the green PVC. Nothing would budge.

What is going on?

[areich]

You can leave it in for longer.

[Carausius]

Are you certain that these spots weren't there when the shekel was first put in the pvc flip?  Perhaps they are encrustations unrelated to the flip.

[DitrasetMan]

It was many years ago. I certainly do not remember anything green on the coin - otherwise I would not have bought it.

Is it possible that it is residue of debris originally on the coin but is not PVC gunk? Perhaps it turned green?

If so, should I soak the coin in 5% solution of ammonia and then multiple distilled water baths?

[bpmurphy]

If it didn't come off with acetone, it's not PVC residue.

Barry Murphy