Verdigris

And can be purchased right here. http://www.wizardcoinsupply.com/coin-preservation/

Yes, verdigris can be removed by several different means. However, most of them end up damaging the surface. My current product, VERDI-CARE™, is able to remove light to moderate verdigris without strippng the surface.

Verdigris is absolutely able to spread. Please see my response in this thread:

https://goccf.com/t/68881

Well, I'm not quite sure how to respond to use of the product. In my experience with metals whether any of the tungsten/moly tempered steels, copper, aluminum, of base iron, the common problem for all (except mercury) is corrosion. (If you're thinking of anodized and chromed steel, go to any junk yard and check out the old cars.) Wish I had a Mercury dime for each time I looked at a machined part (whether forged, extruded, or milled) displaying plastic/permanent deformation, or failure from fair wear & tear initiated by corrosion.

We collectors are stuck between cleaning and not cleaning (or if you prefer "conserving") our coins when presented with particular problems. Oxidation of copper or any copper alloy is the patina we see under our microscopes and call Verdigris. If, since as reported, the coin is "damaged" when treated, is it wise to even pursue a cure?

In several threads in the community, I've seen members offer remedies to members with "problem" coins up to and including "Ketchup". (Now don't think this is the only place that has offered that solution; it's been suggested on other sites also.) While I believe that no action is the appropriate action, I'm certainly open for suggestions especially since I'll never sell my real collection; my heirs will have to fight that battle. I'm thinking the presence of Verdigris helps to prove the coin has not been cleaned.

In my original ROI, I probably should have qualified my request with the phrase: "and not be considered cleaned". Not withstanding further discussion, is there a site or example of the results of this treatment? Can the treatment be readily detected? Since some damage occurs, does it leave clear patchy areas on the coin typical of cleaned copper?

I know that the only way to prevent or halt the corrosion or oxidation of metal is storage in a vacuum or an atmosphere of non-degrading noble gas. (BTW, we're even learning that there is also corrosion in outer space.) Since, here on earth, all nature abhors a vacuum, oxygen will eventually make it into our container. Several thousand of years from now, no one will care. (Well unless you're in the middle of a farmers field with a metal detector and then it becomes a hoard.)

Thanks BadThad for the info.

The oxidation of copper is not the same as verdigris. Verdigris is when copper combines with chemical anions. The oxidation of copper forms copper oxides. Right after being minted a layer of Cu2O, cuprous oxide, forms on the surface. This is actually a nice protective layer. As the layer thickens, the copper will become a deeper red color. With excessive exposure to oxygen and heat, cupric oxide can form (it's black). From my book to save typing:




Verdigris happens when copper is converted to copper hydroxide via exposure to air and water. The highly reactive copper ions then combine with anions like formate, acetate, sulfate, chloride, etc.

The key to conservation is the degree of the vergris. I classify verdigris into three types: light, moderate and heavy. In the case of the first two types, very few copper atoms are removed from the surface. Conservation usual leaves behind almost no trace of evidence, especially with light verdigris, because so little copper has been removed. However, with heavy verdigris, there will be definite pits left behind, so a coin with this type of verdigris is generally not worth conserving. So, to answer your question, YES, light to moderate verdigris is definitely worth conserving.




No it doesn't, it could also mean that someone just didn't get aggressive enough to remove it. I've seen TONS of coins where people tried to remove verdgirs, but left a lot behind.




All you have to do is scroll down in the main forum. LOL

https://goccf.com/t/62434

Most of your questions should be answered after reading that. If you still have more questions, please feel free to ask. You're motivating me to get back to work on my book. It's mostly done, just a few final touches and it will be ready. It's going to answer every question a collector could have about copper coin verdigris.