Weld Mold 4300 description: Weld Mold 4300 is an aluminum bronze alloy used primarily for surfacing and cladding applications. Weld deposits exhibit the highest yield strength and hardness in the Weld Mold family of aluminum bronzes. For best results, clean area of all foreign matter and debris. Either stringer or weave beads may be used with equal success. Weaving should be limited to a maximum of 2 ½ to 3 times the diameter of the electrode. Hesitating at the sides of the weld joint will prevent undercutting. In overlaying iron base metals, apply the first layer at the lowest amperage possible and weave to keep the base metal dilution to a minimum. Apply three passes where possible. A pre-heat of 1000°F is recommended when welding on pure copper.