Here is solder tip, periodically make sure your solder is clean! Oxidation, grease from your hands and dirt can prevent you from having the perfect solder joint so make sure you are working with clean solder (and clean metal!) There are multiple ways to clean it, a quick scrub with a scrubby sponge and hot water and soap, or throwing it in your ultrasonic for a bath. I had found this older sheet of solder and knew it needed a quick cleaning before I work with it. Hope this helps!! #silversolder #soldering #sheetsolder