What is polarity in welding?

Polarity in welding has to do with the direction of the current in the welding process. With direct current (DC) the welding circuit can either be straight, or reverse polarity. When the machine is set for straight polarity, the current flows from the electrode to the weld surface and creates considerable heat in the metal. When the machine is in reverse polarity, the current is backwards and is flowing from the metal to the electrode causing a grater concentration of heat at the electrode.