I got this Maximinus seatertius for like $7. It was covered in some strange teal substance along with some bronze disease. I thought I could subject this coin to more chemicals than your average bag of Cheetos. The end result was... mediocre process: sodium thiosulfate soak was relatively ineffectual for the green. Sodium hydroxide soak didn’t do too much either for the green but took away much of the surface mineral encrustations. Vinegar soak took away most of the blue stuff. Back into hydroxide for the last bit. The green on the obverse was inert and wouldn’t budge.
Valiant effort. The green corrosion is a metal loss but that's what happens. Did you soak it in mineral oil after all you did. Peace Roy
