Tix Solder For Soldering Jewelry & Metals. This is a new set of Tix solder. This solder is the hardest soft solder on earth. It melts at 275 degrees F (135 degrees C) and has a holding power of 4300 PSI. Adheres to all ordinary solderable materials and works with a gun, iron, torch, or soldering machine. It stays white and does not tarnish Includes 20 sticks of solder. Each solder stick measures approximately 3" (76 mm).