In the very near future, I plan to cast some round balls. I know there has been a lot of talk about casting . I apologize if this has been talked about before. The lead I will be using came out of a dentists' office. After cleaning to the best of my ability, and leaving it outside in the elements for several years, it looks pretty good except for something I believe to be glue . When I put it in the pot, will the glue rise to the top like other impurities so it can be scraped off?