Wet or dry. Either is
fine. I would start with the dry "
pop it off" technique and when that stops working you can trying soaking it in DW and brushing. In fact you can alternate. After a few brush-soak cycles then dry it out completely and try working dry again.
However, I think there is more to this coin than just the light coloured earthy deposits. The
obverse bust and lower
face and the
reverse shows sings of corrosion and/or harder deposits. This can complicate things.
Sometimes the earth deposits come off in bits like this due to luck or random cleaning. But sometimes it is because of different surfaces below. In these cases it usually
comes of the nice smooth surfaces easiest and can be hard to get off the rougher surfaces.
Shawn
