Get your sandpaper in three different grades. Sandpaper comes in three grades: coarse, medium, and fine. Sandpaper grades are measured in “grit.” The higher the grit of a sandpaper, the smoother it will make the surface it’s used on. Check the packaging the sandpaper comes in to see what its grit is. Buy some sheets in each grade for your project.
· Coarse-grade sandpaper has a grit of 40 to 80. An 80-grit sandpaper should be coarse enough unless you have significant defects in the surface you’ll be sanding.
· Medium-grade sandpaper has a grit of 100 to 150.
· Fine-grade sandpaper has a grit of 180 to 220. A 220-grit sandpaper should be fine enough for your project, but there are higher grits if you want a smoother finish.
Use open-coat for durability or closed-coat for strength. Closed-coat sandpaper is completely covered in grain, meaning it's a stronger abrasive. Open-coat sandpaper has less grain on it, so it's not as effective, but the extra space on the sheet prevents buildup, which makes it last longer. Use closed-coat sandpaper for harder surfaces and open-coat sandpaper for softer surfaces.