Someone left a question the other day...Do I use lead free solder on the hand mirrors? No, I don't.....If it's lead poisining that your worried about,I have worked with lead solder and lead camming on a daily basis for over 10 years. I have had my lead levels check several times and it has always been fine. Lead free solder doesn't flow as nicely as the 60/40 solder. 60/40 means that it is 60% tin and 40% lead. Most stained glass artists work with the 60/40 unless they are doing a project like a platter or vase, jewelry, ect.... I have seen a beautiful large bowl made from agate slices, (the artist said it was meant to be a fruit bowl)it was done in lead free solder. All in all lead free solder is harder to work with. If you are new to stained glass I suggest you get used to working with 60/40 solder first.