I've gotten into cooking preserves recently and am interested in a copper jam pan -- which is unlined. I thought that I had heard that acidic foods should not be used in unlined copper pans; however, most of my jam recipes include lemon juice. Is this a problem? Will the lemon juice (usually a small amount -- 1/2 to 1 lemon) in jam cause a reaction? Also, if anyone has used a copper jam pan and has any positive or negative comments, I'd appreciate hearing them.