Welding electrode is composed of two parts: core wire and coverage paste, each of them will have effects on welding characteristics. A major part of the common electrodes in Industry have the same core and provided wide rows of characteristics and the application by changing the coating composition. Optimizing the characteristics of the electrodes especially coated is one of the important research areas in electrodes industry. Some of the characteristics of the electrodes can’t be produced in an electrode theoretically and practically simultaneously. For example, arc stability, the remove of slag, separation and low spatter, good mechanical properties of weld metal, and, high penetration, low moisture absorption of coating, low cost of electrode, low smoke during welding and even no dependence on external sources ... are some of these characteristics. So according to the application conditions of electrodes, the first thing a consumer should be aware is the priority of the above characteristics. For example, when penetration is important, use cellulosic electrodes (6010), and where the quality of weld metal is important, select the group of low hydrogen electrodes (7018). According to the diversity of type, diameter and length of the electrodes, the following points should be considered in selecting electrode.
