The modern manual metal‑arc welding electrode combines a central current carrying "core wire", which acts also as the filler rod, and a flux covering which carries out a number of important functions:

1.   It provides a gaseous shield usually of hydrogen and/or carbon dioxide to exclude the air from the arc areas and so reduce the tendency to oxidation etc., of the molten metal.

2.   It produces a slag which assists in the protection of the molten metal and the dual function of scavenging the metal of unwanted impurities and mechanically molding it to a suitable contour in the positions and applications for which the electrode was designed.

3.   It provides a vehicle for adding alloying elements into the weld metal, over and above those elements normally available within the core wire. Thus, quite complicated alloy weld metals can be reproduced from a simple mild steel core wire. It also adds deoxidants to the molten pool.

4.   It can include arc stabilizing elements which permit smooth stable arcing characteristics, even on low voltage AC welding power, or other ingredients to increase arc penetration characteristics etc.

Most covered electrodes these days are designed for use on AC and incorporate special stabilising ingredients in the coating to ensure a steady arc. Some are still designed specifically for DC and used for special applications.

Modern electrodes can be classified into distinct groups based on the major constituents of the flux coating. Each group has its own particular characteristics which govern its usability in various positions and applications. All structural steel electrodes manufactured in Australia are classified under a Standard (AS 1553.1) which indicates by numbers and letters the specified minimum tensile strength, the flux coating type and usability in various positions and on various power sources.

The first two digits after the E (for electrode) are figures indicating 'both of the minimum nominal tensile strength in megapascals (MPa). The last two digits are also meaningful as a "group" and indicate the flux coating and other usability characteristics. All structural electrode packets must carry their classification coding and any two electrodes which carry the same coding can be expected to perform in a comparable manner although minor characteristics may vary. WIA "Austarc" electrodes use the last two "usability" digits as part of their trade name to indicate their general welding characteristics. e.g. Austarc 13S is one of our E4113 type electrodes.

PRACTICE SAFE WORKING HABITS

The best methods are invariably the safest and in the long run the cheapest and easiest. Safety is usually a matter of applied common sense. Apply it. Arc welding uses electricity, produces molten metal, flying sparks and injurious rays and can, if not handled properly, give rise to electric shock, hot metal burns, ray burns, nausea and fire. Intelligently used, it is one of the safest of mechanical/electrical devices and certainly one of the most useful and widely used tools of trade.

Electric Shock

High voltage electricity is a dangerous killer and yet for most of us we have it at our finger tips many times a day in the switches at home and at work. It is safe because it is insulated by the switch, cable or the equipment.

The human body is a poor conductor and therefore will not readily pass current unless the voltage is high. From this point of view, 240 volts and over must be considered as highly dangerous, and all such equipment (power tools, welders, etc.) should be properly earthed. Long primary cables (from switch to machine) are undesirable where they can be cut or burnt, exposing high voltage wiring.

The arc welder is restricted in Australia to a maximum of 80 volts (open circuit) on the welding power side and at this voltage it may generally be considered as "safe". Dry gloves, dry Buckboards or heavy leather boots (not hobnailed) or preferably rubber shoes are effective additional barriers. Moist hands, wet floors and moist clothing all assist in breaking down body contact resistance and increasing the chance of shock. Remember, even a mild shock may cause a "start" which could precipitate an accident‑like falling twenty feet from a hay shed!

The voltages employed for arc welding currents are not dangerous under normal circumstances, but should be treated with care.

Heat

The arc is a source of intense heat, producing molten metal in the fraction of a second. It is therefore a likely source of burns to hands, legs, etc., both by contact with the parts being welded or by molten spatter, slag, etc., lodging on the skin. It can also cause damage by lodging in folds of clothing, the hair, cuffs, etc. From this point of view, the user is advised to wear solid leather gloves, boots (rubber dairy boots are ideal) which come up under the trousers, long cuffless trousers or a boiler suit, clothing of slow burning material (long sleeves) and a cap.

Fire

The same problem of flying sparks and hot metal makes it mandatory to clear the area of sawdust, wood shavings, straw, lacquer thinners, petrol, paints, etc., and choose a sealed concrete floor rather than a gapped wooden floor as the regular welding bay. Similarly, use of an old 44‑gallon petrol drum as a handy table or any containers of unknown contents is indefensible.

Rays

The arc gives off both ultra violet and infra red rays. The former can be particularly injurious, giving rise to an effect similar to severe sunburn. Never work in shorts or bare to the waist ‑ ordinary clothing is adequate protection. Gloves protect the hands. Do not watch the arc with the naked eye. As far as the face and eyes are concerned, a proper hand screen or helmet with protective filter is essential. Use the correct shade filter lens for the current you are using (No. 11 is a good average). Keep these aspects in mind, particularly with regard to the interested bystander or children, dogs etc.

Fumes

Most electrodes give rise to a degree of fume and smoke, which in general reaches a point of annoyance or murkiness in confined spaces before it becomes a health hazard. Welding, however, should always be conducted in well‑ventilated conditions. Welding on galvanized iron can give rise to copious fumes, which cause temporary nausea if ventilation is inadequate and similar precautions should be taken with painted and other coated surfaces.

Finally, remember the people around and give warning before striking the arc, chipping slag, etc. The welder is recommended to always use safety spectacles when chipping, grinding or in other ways preparing or finishing a welded joint. Your eyesight is precious, and hot flying slag or a spark stream from a grinding wheel can be dangerous.