Is It Possible To Stop Verdigris/Bronze Rot

Well depends on how much you care about the coin I suppose. I hold a doctorate in chemistry and anything can be reversed. Hard to get the students to understand nothing is ever lost we can always react it back. Fish chemicals can be fun to try if you are interested. Product called api stresscoat but only a little bit in a few hundred ml and I warn you it will turn the coin black if you forget about it. But you can knock out that green chloride. Then when you get what you want done you probably should seal the area with wax a bit as it is prone to react again. Then of course move to Arizona and stay off the islands off Florida with your coins. But honestly, if you do this you don't just change the area with the issue, you change the patina of the whole coin darker. But if the coin is about to be lost you can stabilize it potentially but it will look quite different. Even if you use a q-tip and only apply to the affected area that area won't go back to looking like the rest of the healthy part of the coin with the regular patina. But it can stabilize and you can put a bit a wax as I said. I did do some experiments a few years ago. Greater good is the equation you start to apply when a coin is in deep trouble. No promises of course.

I've always had luck using olive oil it will soften the material to where the crusty deposits can be removed. The only draw back is that it has a tendency to darken the coin.