Tip: Spotting PVC Damage

[Guest Stujoe]

 

Here is an example of a coin with advanced PVC damage. PVC damage can of occur when a coin is stored in certain soft plastic holders. The things (plasticizers) added to the PVC plastic to make it soft can leach out onto the coin and cause this kind of damage over time.

 

The PVC on the coin above can be seen as the green areas. The PVC damage is so advanced on this coin that you can see where it has eaten into the coin and left pits in it. In less advanced stages, the PVC residue may be removed with a solvent such as acetone with little damage but, for this coin, it is too late. Even after removal, the damage to the coin would be obvious.

 

I have heard that one sign of the presence of PVC softeners is a 'new shower curtain' smell to the holder or coin. However, it is much better to ensure that whatever holders you use are archivally safe and free of PVC plasticizers before placing a coin in them than to be unsure and try to guess.

 

I also always remove any coin that I buy from the dealer's holder and place it in my own which I know are ok.

 

Finally, here is a closeup of the PVC on the coin:

 

 

 

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[just carl]

Just out of curiousity how do you know that the substance you are referring to is caused by PVC? What is the chemical composition of the greenish discoloration? On man coin forums lately it has become a standard to say PVC caused this. I think without a chemical analysis of the compound it would be impossible to tell what the substance actually is composed of. Further, it is true that a substance is added to Vinyl products to make them more flexible. These are normally called Phthalate Plasticizers. They actually do leak Gases and usually of the Chlorine compound variety. However, eventually there is very little left to leak out of the product and it becomes less flexible but more stable. This leakage does not go on for ever since there is a limited quantity present. The PVC itself can not even start to melt until 413F (212C) indicating that the PVC itself can not do damage under normal temperature conditions.

So again out of curiousity how would a person be able to identify so called PVC damage?

An example of other damage would be the reaction of the Copper in the coin with normal elements present in the air. If the coins Copper becomes exposed to just plain air the greenish discoloration would occur naturally. As is common with Copper when exposed to air the Oxygen attacks the Copper to form (CuO2). This is the mormal darkening of Copper. Then if moisture and Carbon Dioxide is present they attack the (CuO2) and form the greenish layer of Copper Carbonate [CuCO3-Cu(OH)2]. In some areas of the country where there are or were Sulfur rich Coal burning factories or power stations, the general area has SO or SO2 in the air. This will combine with the Copper Carbonate to form Copper Sulfite or Sulfate. Highly greenish crystaline formations on anything that is Copper.

So not to be repititious but how do you know that the contamination you show is PVC?