For stringent requirements regarding low porosity levels, SSAB proposes that the primer is removed prior to welding. Evaluation of fillet welds that are welded in the horizontal position show that the porosity level is typically up to some percentage of the total volume of the weld metal.

Out of position welding, which means welding in other positions than the horizontal, is also enhanced by removing the primer in the joint. In these situations, there may be a tendency for insufficient bonding of the molten weld metal to the joint if the primer is not removed. This matter can cause lack of root fusion and lack of fusion in the joint.