PVC

deltadon

Just received notification from PCGS that two coins (both silver) were PVC coated. Can anyone explain what this means and why PCGS would reject for grading because of this. Both coins are beautiful mint state with original lustre.

fcloud

Welcome to the boards. It is a long subject but the PVC comes out of the plastic in the soft flips and attaches itself to the coin. It can actually etch the surface of the coin. I am sure someone here will be able to tell you the best way to remove it. The color of it is light green, and even after it is removed the coin still could be rejected because of the damage it causes.
Tony

coppercoins

PVC (polyvinylchloride) is a softener used in some plastics to keep them from going brittle. It also breaks down over time and turns into a thick, green slime. Some coin holders contain PVC. This PVC, after being stored for a while, coats the coin it is holding.

The reason the grading company will not grade the coin with PVC on the coin is because PVC is damaging to the coin's surface. Depending on how long the coin has been in the holder that caused the problem, it may be removable. They will not grade the coin, however, because if the encapsulate a PVC coated coin, the PVC will remain on the coin actively eating at the coin's surface. It must be neutralized by removal before they will entomb the coin.

PVC can be cleaned off of most coins with pure acetone, available at Wal Mart. Use a liberal amount on a q-tip and lightly pull off all the film on the coin with the q-tip.

Conder101

No No No! PVC is NOT the softening or plasticizing agent! PVC is the actual plastic and it by itself is fairly beneign. The plasticizer is normally an phenoylated oil and by itself it is harmless too. The problem comes for the two together.

As PVC ages the plasticizer leaches out and get on the coins. Not a problem so far. Also as it ages the plastic begins outgassing HCl (Hydrogen Chloride). Not good but normally not a problem in a well ventilated area but most coins aren't kept well ventilated. Unfortunately the plasticizer will absorb this HCl gas so the concentration builds up in the plasticizer coating the coins. Then the final problem, the plasticizer is also hydroscopic absorbing water vapor from the air. When the absorbed HCl mixes with the absorbed water it creates Hydrochloric acid which the plasticizer is then holding in close contact to the metal of the coins. Hydrochloric acid is an extremely powerful corrosive agent and it begins etching the coins. The green color comes from the reaction of the acid with the copper in the alloy of the coin which forms Copperchloride, a green colored compound.

Even if the coin has bee removed from the PVC holder the contaminated oil on the coin can continue to react with the coin so the services will not holder the coin and be liable under their guarantee for any changes. And as fcloud says if the coin has been coated with the slime too long even if the plasticizer is removed the services may reject it because of the damage that has already been done to the surfaces.

MadMonk

Condor101 is absolutely correct. I thought I was the only person who knew this.
As stated, it's troublesome, and to get them back and remove the PVC doesnt guarantee encapsulation.
Call ET Kointaner for thier newest PVC remover. If you have a little mad scientist in you,
try a three stage dip of acetone. Rinse and dry real well. I.e., when you think your done rinsing, rinse some more. Warm water. Pat dry real well.

1jester

Thanks for the info, folks. Madmonk, could you please elaborate further on the 3-stage rinsing process? Do you dip the coin in a container of acetone? And if so, for how long? Should the acetone be 100% pure, or do you mix it with something? After the first dip, do you then rinse it with warm water, then dry it? That constitutes the first stage? And then repeat the whole process at least twice (dip in acetone, rinse with water, dry)?

Thanks a lot; I intend to try to salvage some PVC contaminated coins, like an 1878-CC PL dollar in MS, and an 1899 dollar in MS.

nwcs

Personally, I just use acetone in a very simple way. Use 100% pure all the time, never anything else. I soak the coin in a dish with acetone for as little as a few minutes to as much as a day, depending upon the coin. Then rinse it with some acetone and then soak again for a bit to get any remaining crud off that might have settled on it. Then rinse real quick again and air dry because acetone evaporates very quickly.

nwcs

If you do use water, use distilled water. Tap water contains other chemicals which can react with the coin. And I recommend after rinsing with water to dip in acetone as that is a better way to dry the coin than patting.

1jester

Thanks, nwcs!!!

Libertad

I use a few ceramic cups with a half inch of acetone in each, dipping/soak for a few minutes, then extract and move to the next, etc.

Just a word of caution, acetone is EXTREMELY flammable and the vapor is evaporating from the fluid from the get-go, getting more concentrated near the source, but can rapidly fill a small room to the point that flash burning is possible/likely from a remote source of flame or spark.

I've found a small drop to a small pool of green liquid in the bottom of the acetone-filled cups after removing from the first acetone bath, on coins that were certifiably PVC damaged. The slime sticks together.

Haven't had to use Qtips unless the surface is blackened from the damage to silver.

1jester

Just an update: after an overnight soak, all the coins cleaned up extremely well, at least from the PVC. Unfortunately, on some of them, many small pits were left after the PVC damage. Too bad, because one was an 1885-O Morgan, about MS-64DMPL, and another was and 1878-CC, also MS-64+ DMPL. The 1899 was undamaged, and looks about MS-65.