How to choose the grit size of the abrasive grain?

You need to choose the grit size of sandpaper depending on the particular job you are trying to accomplish. For heavy sanding and stripping, you need coarse sandpaper measuring 40- to 60-grit; for smoothing surfaces and removing small imperfections, choose 80- to 120-grit sandpaper. For finishing surfaces smoothly, use a super fine sandpaper with 360- to 600-grit.

Many jobs require you to “go through the grits.” This means you start the project using lower-grade grit and use finer pieces of sandpaper as you progress. Each time you advance to a higher grit sandpaper, you remove the scratches from the previous layer.