Thoriated tungsten heavy metal electrodes (AWS classification EWTh-2) contain a minimum of 97.30 percent tungsten and 1.70 to 2.20 percent thorium and are called 2 percent thoriated. They are the most commonly used electrodes today and are preferred for their longevity and ease of use. Thorium increases the electron emission qualities of the electrode, which improves arc starts and allows for a higher current-carrying capacity. This electrode operates far below its melting temperature, which results in a considerably lower rate of consumption and eliminates arc wandering for greater stability. Compared with other electrodes, thoriated electrodes deposit less tungsten into the weld puddle, so they cause less weld contamination.

Thoriated tungsten heavy metal electrodes are generally used for DC electrode negative or straight polarity applications such as carbon & stainless steels, nickel alloys and titanium, as they operate well even when overload with extra amperage, and then improve the performance of welding.