The three primary categories of electrodes—cellulose, rutile, and basic (low-hydrogen)—obtain their name from the coating type. Electrode coatings help optimise performance for various applications by influencing how quickly the slag freezes; penetration (deep, medium, or mild); and deposition rate. The coating also contributes to good arc initiation, easy restrikes, puddle control, and a stable arc with minimal spatter.
Basic. Basic electrodes offer an arc with medium penetration and excellent mechanical properties. The coating is low-hydrogen iron powder, TiO2, CaCO3, and CaF2 (calcium fluoride). The coating is of medium thickness, and the addition of iron powder increases deposition. It freezes relatively fast to enable flat, horizontal, vertical-up, and overhead welding. Basic electrodes such as E7018 are used for critical welds in structural steel construction, bridges, ships, and offshore oil and gas applications where mechanical properties are important.