Electrode re-baking
The high-temperature heating of stick electrodes prior to use to fully drive out absorbed ambient moisture.
The coating of stick electrodes absorbs moisture from the air. During welding, the water is split in the arc and hydrogen can migrate into the weld. This shows up as porosity, but worse are cold cracks, which often appear only hours later. This is especially critical with basic electrodes and high-strength steels. Therefore: Basic electrodes that have absorbed moisture must be placed in a drying oven before use. Rutile electrodes are less sensitive, but you should still store them dry. Cellulose electrodes, on the other hand, must never be dried; they need their moisture for penetration. Follow the manufacturer's instructions for drying and store opened packages in a heated quiver.