I don't think there's much you're going to be able to do to help that coin. Some of the ancient collectors might have some ideas.
Leave it alone. The verdigris is heavy and if you remove it there will be pits left behind. If you really like the coin and want to halt the verdigris, rinse well with acetone to dehydrate the verdigris and put the coin into an air tite holder.
I tried verdi-gone on some Indian cents that were pretty bad, not as bad as yours, It helped a little, but it doesn't damage at all, it's very safe, IMO.
Please order VERDI-CARE™ and not VERDI-GONE™. It's my newest product and vastly superior to VERDI-GONE™. Additionally, it will neutralize any verdigris remaining after conservation and protect the coin from future corrosion.
The man who invented and makes the stuff tells you flat out not to bother using the product and still you persist ? I'm apologize if my question offends you, but I mean, why would you even consider the idea after that ?
http://www.wizardcoinsupply.com/files/images/Verdi-Care-FAQ.pdf http://www.wizardcoinsupply.com/files/images/Verdi-Care-Instructions.pdf Protected from air and water, virtually forever.
