I picked up this Probus in a group lot, how could I get rid if the crud without damaging the rest of the coin? Thanks.
It looks like it has corrosion problems, and a couple of spots (light green) look like BD, I would soak it in a mixture of distilled water, soda ash and bi-carbonate soda and let all the adhesion melt away change the mixture every week you will probably lose a lot of patina, but at least you will see detail underneath if it hasn't corroded away.
Unfortunately, the corrosion has irreversibly altered the surface of the coin. Removing the corrosion as Ancient Aussie suggested will probably improve the overall appearance of the coin, but the surface details are gone. Here's a coin that had much more corrosion than yours, which I removed through electrolysis. You can clearly distinguish between areas that weren't destroyed by corrosion (on the left side of both obverse and reverse) and those that were. Your coin has not suffered nearly as much as this coin, so it will end up looking better that this poor thing, but the areas under the really heavy corrosion will look like similar to the right side of the reverse of this coin if you remove the corrosion. Also, I'm not convinced that the bright green spots on your coin are bronze disease, but if they do turn out to be so--that is, if a fluffy green powder starts to build up over these spots--you must treat it or it will destroy your coin. Bronze disease is a serious problem but fortunately, easy to treat with repeated distilled water soaks.
