How would you treat the Verdigri?

I would ask a question or two and make a couple comments.

1 - what makes you think it is verdigris ? I'm asking that because I've been sitting here looking at the pics, including blowing them up to 150%, and I can't see anything that really looks like verdigris. I realize that may be due to the pics, and perhaps you can see things in hand that I can't see in the pics - like color. If it's verdigris it should be green and I can't see anything on either coin that looks green. All the spots look either black or brown to me. So in hand, do they look green to you ?

2 - more of a comment than a question really.

There isn't anything stronger than Verdi-Care that you can use on verdigris. Sure there are harsh chemicals, but all of them will damage the coins far worse than what the corrosion has done. Verdi-Care is the one and only thing that will safely remove verdigris. And even then, there very well may be damage underneath that has already damaged the coins.

3 -

There are two things that are needed in order for verdigris to form - moisture and the air. That's what causes it. And those two things go hand in hand, one is within the other. So if verdigris is already there, they way you prevent it from getting any worse is by placing the coins in a container where you can limit the amount of moisture in the air within the container. There are two ways to do that, use an airtight container, or use a desiccant inside the container. Do either one of these things and the verdigris will not get any worse. It won't go away, but the coin won't corrode any more either. So the amount of verdigris will not increase.

4 -

Why not ? Verdigris isn't "contagious", it simply is. It can't jump or transfer from one coin to another. Verdigris isn't the cause of corrosion, verdigris is merely the result of corrosion. The green stuff that you see, well, that's what copper is turned into as a result of the copper corroding. It literally is no longer copper or metal, it has physically changed into a completely different material. One that happens to be green in color.

Now perhaps you already know these things, but your comments make me think perhaps you don't. And that's why I posted.

 

It's certainly possible that some of it was PVC residue, it's definitely not unheard of for both to be on the same coin.

That said, when verdigris forms and for sometime after it is a powdery substance. It doesn't get hard and crusty until after an extended period of time, typically years. But when it is still powdery any contact with virtually anything from plain water or any other liquid, or even your finger will brush it away. But the hard stuff, doesn't work like that. It is the hard, crusty verdigris that Verdi-Care safely removes.

Verdigris, other than the color, is very much like rust on iron or steel. If you've ever handled anything rusty, when you take your hands away they are going to have rust on them. You can even take a rusty object and rinse it in water then dry with a cloth and the rust on the object will be gone. And what isn't washed away by the water will be on the cloth. The effects of the corrosion that produced the rust will still be there on the object, but the rust will be gone. Verdigris behaves in the same manner while it's still powdery.

 

That's completely normal. As for more attention, there isn't anything else you can do. The spots that remain, they're permanent.

And just to clarify something - the verdigris, the green stuff itself, is not in any way corrosive.

For example, you could scoop some verdigris up off of one coin and deposit it on another coin. Then place that coin in a airtight container, and leave it there for years; after that time had passed you could take the coin out of the container, literally blow the verdigris off the coin, and the coin will not have been harmed at all. That's because verdigris is not corrosive.

 

It's not corrosive on the host coin either, nor is it corrosive on any other coin.

I don't know how else to explain this. The verdigris, the green stuff, that is literally what used to be copper. But it is no longer copper, it has been chemically and physically changed from copper into verdigris as a result of the corrosion caused by the air combined with the humidity within the air.

Take away the air, corrosion will no longer occur. Take away the humidity, corrosion will no longer occur. Do either one of those two things, but leave the verdigris on the coin, and corrosion will no longer occur.

To put it another way, the corrosion eats the copper (the metal) one thin layer at a time. This happens at the molecular level. And when it is done eating all of the elements out of the metal that it wants, what is left behind is the green stuff, the verdigris. And yes, as long as the coin is stored in the same place and under the same conditions, the corrosion will continue and even more verdigris will be produced and build up upon the verdigris that was previously there.

If you put a cow in a pasture it will eat the grass. And when it comes out the other end it is no longer grass. Verdigris, is what comes out the other end.

 

No, it isn't corrosive at all - on any coin ! It's not corrosive on coins made of an alloy that has copper, or even traces of copper, in it. Nor is it corrosive on pure copper.

The simplest way to put it is this - verdigris is the RESULT of corrosion, not the CAUSE.