As you sand, it’s tempting to help the sander along by pressing down hard to get the job done more quickly. But there’s a problem with doing that. The extra pressure slows the sander’s pad down, reducing its ability to overlap swirl marks and minimize scratches. Plus, the pressure may cause the sander’s motor to overheat, shortening its life. Another temptation to avoid is tipping the sander up on edge to “rub out” a large scratch in the surface. While this may remove the mark, it’s likely to create a larger, more noticeable depression. One good way to avoid rounding over an edge is to provide support for the sander as you work. A backer board the same thickness as the workpiece provides the necessary support.