Preheating the casting is recommended only when absolutely necessary in order to prevent excessive stresses. Steel electrodes are used at low current to limit the amount of dilution from the casting. The recommended polarity and current for this electrode is dc reverse (electrode positive). The weld beads deposited by these electrodes should be short and widely separated, followed by a light peening after each deposit. After welding, the slag should be completely removed, especially prior to painting.