Arc blow is the usually unwanted deflection of the Arc during Arc welding. The welding current flowing through a plate or any residual magnetic fields in the plate will result in unevenly spaced magnetic flux line. These Gheven flux line can , in turn, cause the arc between the electrode and the work to move during welding. The best method to eliminate are blow is to use alternating current since alternating current changes directions, the flux line don't become strong enough to bend the are before the current changes direction.