The electrode is coated in a metal mixture called flux, which gives off gases as it decomposes to prevent weld contamination, introduces deodorizers to purify the weld, causes weld-protecting slag to form, improves the arc stability, and provides alloying elements to improve the weld quality. The electrode is either consumable, in the case of gas metal arc welding or shielded metal arc welding, or non-consumable, such as in gas tungsten arc welding. Electrodes are a necessity in welding. Molten metal becomes brittle or has other negative qualities when exposed to air as it absorbs nitrogen and oxygen. Slag covers protect the molten metal during welding from the surrounding atmosphere. The slag cover is usually obtained from the coating of the electrode.
Services workshops have essential capabilities for ensuring the correct quality in terms of dimensions, tolerances and wear-resistance.