Support BladeForums! Paid memberships don't see ads! I only sand in one direction. The goal is making finer and finer scratches on the metal until they are so thin you can't discern they are there. To make them blend together you need to move the metal in one direction only with long smooth strokes. Move down one grit if you aren't getting the scratches to blend then move up the grit for each stage, I count the strokes to keep them evenly applied. A hard foam backer helps keep flats flat and gives nice straight lines.