Soldering a Vertical Seam

This is where having a sharp point pays off. Reduce the torch’s heat, then while holding the iron at a shallow angle with the tip against the metal, press the solder stick against one facet of the tip until a drop of melted solder forms. Use the iron to spread the drop across the seam; each drop adds another layer, and the heat of the iron on the copper draws the solder into the seam to make a watertight seal.