Looks like
electrolysis? OK if its a very last resort, but you will have a lot of
pitted and rough surfaced coins with
electrolysis and more will be ruined than saved.
Folks will be harsh on
electrolysis as a primary method in this
forum. While I employ it myself for difficult coins that won't respond to other less drastic cleaning techniques, we all would encourage you to try to avoid it if possible.
What is the method you used? Are you interested in learning the less destructive methods? If so, there are many who would jump on a chance to
help.
Don't get discouraged when folks jump all over you for harsh cleaning though, just mark it up to experience and keep cleaning!