Can PVC spread from one coin to another?

59Horsehide

Tried to find the answer with no luck. If coins are in 2X2s' and one has PVC/Verdigras, and is stored in the same box as other coins, is it possible for the PVC to spread to other coins? What causes PVC to form on a coin? I know it is "chemistry" but I do not understand the process.

Oldhoopster

The short story: The plasticizer used to soften the PVC breaks down under certain heat and humidity conditions. This residue can form hydrochloric acid.

I don't believe it would migrate unless you reuse the flip or a contaminated coin is in physical contact with another coin. However, if the storage conditions caused problems with one coin, there may be others if the were in PVC flips.

Also, it takes a little time before the green slime is visible. Coins may have exposed to PVC residue in the past, and are starting to turn later

59Horsehide

Thank you, Oldhoopster, for your reply. I will add the PVC problem did not happen from my flips. The coin in question had PVC showing before I placed it in a flip. Now wondering if I should store it separately from other coins.

Oldhoopster

@59Horsehide said:
Thank you, Oldhoopster, for your reply. I will add the PVC problem did not happen from my flips. The coin in question had PVC showing before I placed it in a flip. Now wondering if I should store it separately from other coins.

If the coin still has plasticizer residue on the surface, figuring out how to store it is the least of your worries! You need to remove the residue or the acid will continue to react with the surface of the coin. The longer it stays on the coin, the more damage will occur!!!

You can use acetone or xylene to remove it without damaging the coin's surface. Both are flammable chemicals, so you want to make sure you know how to handle them and the potential damage it can do to you and your surroundings (counters, pipes, soaking container, environment). There are a number of threads in the archives that can help point you in the right direction.

When you're done, don't forget to put the coin in a new flip. Also, get rid of any of the soft PVC flips if you haven't already done so

59Horsehide

Great advice but still have a question. Can acetate be used on copper coins with a PVC problem? I spent a good hour last night trying to find the answer but all I am getting is uncertainty. Some say "No, it will change the coins appearance". I was not able to find any definite "Yes" response or any instruction as to using acetone with a copper coin. I am discovering my Lincoln cents from 1909 to the mid 30's (given to me by my Grandmother in 1960, stored in a coffee can for all those years) are the problem here. I put them in flips in the early 70's and the flips are the PVC contained kind. I ordered 500 mylar flips last night to replace the old flips. I would like to treat these coins, if possible, before using the new flips.

Any suggestions or actual experiences would really be appreciated. Sorry to be drawing this out.

Namvet69

I think the big unknown is the strength of the off-gas over time. IMO. Peace Roy

coinbuf

@59Horsehide said:
Great advice but still have a question. Can acetate be used on copper coins with a PVC problem? I spent a good hour last night trying to find the answer but all I am getting is uncertainty. Some say "No, it will change the coins appearance". I was not able to find any definite "Yes" response or any instruction as to using acetone with a copper coin. I am discovering my Lincoln cents from 1909 to the mid 30's (given to me by my Grandmother in 1960, stored in a coffee can for all those years) are the problem here. I put them in flips in the early 70's and the flips are the PVC contained kind. I ordered 500 mylar flips last night to replace the old flips. I would like to treat these coins, if possible, before using the new flips.

Any suggestions or actual experiences would really be appreciated. Sorry to be drawing this out.

Well first no the PVC will not "travel" between flips unless the window of the 2X2 of the one affected is torn, and another coin also in a 2X2 with a torn window came into contact with each other. Now the question on acetone, the simple answer is generally no but it depends. I have on some occasions seen a change in the color of the coin from an acetone rinse, this is not chemical reaction of the metal but rather some other agent that is on the coin's surface that the acetone does not remove. This is not the norm but I did see it on a few coins years ago when I was doing lots of experimentation on Lincolns so I would be better able to identify cleaned/altered color coins. However in your case the benefit of removing the PVC far outweighs the possibility of a couple coins changing slightly. And if the PVC has eaten into the coin surface you may see a color and texture change, nothing you can do about it and while unfortunate its still better to remove the PVC than do nothing.

Get good pure acetone (not fingernail polish remover) and two vessels (glass is good) that is big enough to place a few coins into without the coins touching and that has a secure lid. Pour in enough acetone to cover the coins completely and let soak for an hour and check to see if you notice any changes. I have a pair of plastic tongs that I can pick the coins up by the edges with and then gently shake back and forth to dislodge any stubborn gunk. Let soak for as long as it takes for all the slime to slip off the coins. Then place the now PVC free coins into another fresh batch of acetone and give a quick shish to make sure no contaminated acetone from the first bath stayed on the coin set on a soft cloth to dry and you are ready to place in the new flip. You will need to change the acetone in the first and second bath containers often or you run the risk of some of the contaminated acetone and PVC ending up on the coins and spreading that way.

Remember that acetone is very flammable so use in outdoors if possible and away from any flame or ignition source.

59Horsehide

Thank You, coinbuf. Very much appreciated. Thanks to everyone who responded,