The answer is longitudinal. There are two types of waves: transverse and longitudinal. Transverse waves are those whose vibrations are perpendicular to the direction of the wave. Longitudinal or compression waves are those whose vibrations are in the same direction as the wave. Sound is caused by the compression of vibrations of molecules.
The root pass is made with a 5/32” (4.0mm) diameter electrode. A cellulosic electrode (E-XX10) is being used. The root pass is welded with reverse (DC+) polarity.
