What Should I Use?

First, always try just acetone. As long as it's clean and fresh, it's the best thing for taking off some of the materials. it's about the safest product out there.

Distilled water soak is also a good approach for removing the crud. Just clean out the water daily.

Also trying a distilled water soak with repeated freezings. Once the water works it's way into the crud, then the enlarging of the ice molecules can break off pieces of the stuff.

Think someone on the site is mentioning denatured alcohol. Haven't tried that one yet.

Olive oil soak is good for deeply incrusted crud. Check many ancient coin websites for the cleaning method used.

http://www.provincial-romans.com/cl...g_romans.htm

http://www.ancient-times.com/info/cleaning.html

:( Kinda miss the green patina.

I dunno... The Green was what was corroding it-which I didnt really want at all. It was actually much grosser than the scanner projected it as. And on top of that, I didnt strip the coin (It is made of copper, not black metal) On the reverse you can see some of it from when the coin was bashed around in a 2 euro bin for years. The green gave it character while destroying the coin at the same time.

Sounds good... I think the black will protect but if it starts to rust I'll let you know you were right.