What are the two methods of striking an arc in welding?

Striking an arc in welding is a critical initial step in the process, and the correct methods involve practical actions that help establish the welding arc between the electrode and the workpiece. Scratching and tapping refer to techniques used to initiate the arc.

Scratching involves dragging the electrode across the surface of the workpiece in a quick motion, similar to how one might strike a match. This motion creates a high voltage that breaks down the gap between the electrode and the workpiece, igniting the arc. Tapping, on the other hand, can refer to lightly tapping the electrode against the workpiece to start the arc; it creates contact and helps in establishing the plasma necessary for welding.

Both methods are effective for starting an arc because they produce the necessary electrical contact and initial conditions for igniting the welding arc efficiently. In contrast, the other options do not pertain to standard arc initiation techniques in welding.