I have a group of about nine that have been soaking for nearly a year. Every time I take them out I can get a little more crude off them, but not enough. I have a bad feeling they are going to turn out to be slugs, but I will keep at them. They are the last uncleaned coins I bought. I just got tired of the same 4th century coins in bad to not so bad shape. If I could find some I could feel reasonably certain there would be something else under the crude besides the slugs and the Constans/Conatantius II soldier and standards/fallen horseman coins.