Shielded Metal Arc Welding (SMAW / MMA)

In stick welding, the electrode melts off and the coating burns to slag and shielding gas. The slag protects the still hot weld from the air until it cools. If the electrode is damp or you weld too fast, you get pores and a weak weld. Make sure the coating is dry and intact, and chip off the slag cleanly after welding. Don't quench the weld, but let it cool slowly so it stays tough.