Does anyone have any idea what variety this bus half is? The rim is weak in the strike with smudged stars I am also curious about the uneven grey wash over the coin, from the darkness of the sheild and the darkness that collects around devices. The detail around the fields near the nose and mouth have some motting colors. WHat causes that?
I think it might be the 108a. I can't tell if the die crack is there or not in your picture. If the crack is there this is it.
IMO, no. It appears to me to be just toning from age, not crud. And acetone is mainly for crud and won't affect toning.