No, that doesn't look like PVC damage. PVC causes a more slimy type of residue, your residue is dry and flakey. It's just plain old verdigris. A good coin for spending.
Maybe, but I would disagree Thad. PVC is only slimy on the beginning stages. In later stages it dries out and turns flakey. In even later stages it turns color as well, first into a whitish and then into a brown and sometimes even black crust. That looks exactly like mid-stage PVC to me.
Well, "PVC damage" and verdigris are one in the same on copper containing coins Doug. The formation of copper salts are the end result. I consider the early stage to be primarily the slime stage which is mainly organic based. That's why acetone is able to remove it. As the hydrochloric acid eats into the surface, verdigris is formed and the carbon-based molecules degrade. At the later stages, regardless of the mechanism, all that remains is verdigris.
Well I'm no chemist like you Thad, but this is the first time I have ever heard anyone say that PVC damage and verdigris are the same thing. Even though you are the chemist I have hard time agreeing with what you are saying. I can see where both can cause similar damage to coins, but as I understand it verdigris is the corrosion of copper caused by moisture and acid compounds in the air. Where PVC damage is the release of plastecizers (softeners) from the plastic. Yes I understand that those softeners turn acidic and that that is what actually damages the coin. But to say they are the same thing, that's going a bit too far in my mind. By the way, acetone will remove even dried up PVC residue. But acetone won't even touch verdigris, other than to remove the soft powdery parts and plain water will do that much. That makes it harder for me to consider them the same.
Actually it can be done... one of my bosses with years experience as a professional said that on like Franklin Halves you can remove toning....and it wont harm the coin except for a microscopic layer of silver being removed...repeated dippings are something else.
Well I'll tell ya what. You get a toned coin, pick one of your choice. You go dip it in acetone yourself. See it with your own eyes. Then go talk to your boss.
Doug, I can't wait to get my book done, I cover this topic in some depth. The actual damage/corrosion is NOT from the plasticizer, it's from the hydrochloric acid degradation product. The HCl eats the metal and forms silver chloride and copper chloride (one type of verdigris). If you remove the plasticizer with acetone soon enough, the HCl has not done much damage. This is why we're able to save some PVC damaged coins with little noticable damage. However, over time, it is indeed verdigris (by definition) that is formed because air, moisture AND chloride ions come into play supplying all the necessary ingredients. So yes, they are one in the same.
100% agree. Acetone will not remove toning and, as Doug said, try it for yourself and you'll see. The ONLY way to remove toning is with acids. An organic solvent like acetone is far too weak to break the silver sulfide layer.
