Electrode with special covering for welding aluminium-silicon cast alloys. In welding, hold electrode perpendicularly to workpiece, with a short arc. Wall thickness greater than 10 mm and larger workpieces will require preheating from 150˚C to 250˚C. Since slag residues are corrosive, they must be completely removed from the weld bead. Electrode serves well as consumable, in oxyacetylene welding. The covering being hygroscopic, electrodes must be stored in an absolutely dry location, or redried if required.