Just some info for new techs or people looking into soldering... I originally used Alpha Fry 60/40 (60% tin/40% lead) for years until recently I had been using Kester 60/40 for the last few months. Well tonight I found a roll of Alpha Fry in my cabinet to use on a project and immediately started choking and coughing. I decided to A/B test them. The Kester makes barely any smoke and fumes at all and the Alpha Fry smokes like a chimney. No wonder. I also found the Kester makes smoother looking solder joints but is mainly just a cosmetic thing, never had any issues with bad joints with either. Good things to know, will be sticking to Kester just for the reduced smoke/fumes.