Extrusion or the Dipping procedure:

Either the extrusion or the dipping procedure applies the covering on shielded metal arc electrodes. Extrusion is much more broadly used. The dipping procedure is used primarily for cast and some fabricated core rods. In either case, the covering contains mostly of the scavenging, shielding and deoxidizing materials. Mostly SMAW electrodes have a solid metal core. Some are build with a fabricated or composite core containing metal powders encased in a metallic sheath. In this latter case, the reason of some or even all of the metal powders is to generated an alloy weld deposit.

In addition to developing the mechanical properties of the weld metal, electrode coverings might be designed for welding with alternating current (AC). Along AC, the welding arc goes out and it is re-established each time, the current reverses its direction. For good arc stability, it is essential to have a gas in the arc stream that shall remain ionized throughout each reversal of the current. This ionized gas makes achievable the reignition of the arc. Gases which ionize readily are available from a variety of compounds, by including those that contain potassium. This is the incorporation of these compounds in the electrode covering that enables the electrode to operate on AC.

In order to increase the deposition rate, the coverings of some of carbon and low alloy steel electrodes contain iron powder. The iron powder is an another source of metal available for deposition, in addition to that achieved from the core of the electrode. The occurrence of iron powder in the covering also makes more efficient use of the arc energy. Metal powders other than iron are often used to alter the mechanical properties of the weld metal.

The thick coverings on electrodes along relatively large amounts of iron powder enhance the depth of the crucible at the tip of the electrode. This deep crucible give helps to contain the heat of the arc and permits the use of the drag technique (described in the next paragraph) to maintain a constant arc length. While iron or other metal powders are added up in relatively large amounts, the deposition rate and welding speed enhanced usually.

Iron powder electrodes along thick coverings decrease the level of skill needed to weld. The tip of the electrode might be dragged along the surface of the work while maintaining a welding arc. For this purpose, heavy iron powder electrodes often are called drag electrodes. Deposition rates are high, however, because slag solidification is slow, these electrodes are not appropriate for out-of-position use.