I figured I would start a thread to show off some of the before and after pictures and try to give some tips or directions on each example given.
This large cent had a green hard stubborn "cement-like" layer , unfortunately it also had a small amount of pitting hiding under this layer but despite this i'm very happy with the results . I used a couple of stainless dental picks on the surface of this coin because the green corrosion was so hard . This is a very slow and careful as to not scratch the coins surface.