Sandpaper comes in many different varieties. Each home project you do, whether you are sanding wood or metal, requires a different type of sandpaper. Choosing and using the correct sandpaper will affect the success of your project. Learning the different types, numbers, grit and grades of sandpaper available will come in handy when you need to smooth a particular surface.
Used on surfaces such as wood, metal and plaster, dry sandpaper works well in repairing the finish on wood floors, wood furniture, exterior wood surfaces, interior walls and painted metal surfaces.
Wet sandpaper is commonly used on metal and fiberglass surfaces or to reduce dust on interior walls. Wet sandpaper has its abrasive material applied to either a cloth or sponge backing. A small amount of water is applied as a lubricant to help polish the surface. The sponge type contours to curves and corners and retains water longer than the cloth-backed type. Wet sandpaper lets the grit float over the object being sanded, producing a more even surface.
Power Tool Sandpaper
Power tools use specialized sandpapers. These include discs, pads, drums and belts. If you have a sanding power tool, keep an ample supply of the sandpaper it requires on hand so you will be ready to complete household jobs as they arise.
Sandpaper Grit Sizes
Once you have determined what type of sandpaper your job requires, pick the grit of sandpaper you will need. The bigger the number, the smoother the paper. The lower the number, the coarser the paper. You can accomplish most household sanding jobs using grits from 60 to 80. For smooth surfaces, use a grit rating of 100 or higher. Use sandpaper with a grit number lower than 50 for very rough surfaces.
Low Grit Sandpaper
Coarse or very coarse sandpapers have grit ratings below 50. When used on wood, they can remove heavily weathered paint or even an entire surface layer. Use low grit sandpaper when refinishing a wood floor with a belt or disc sander. When used on metal surfaces, it can rapidly eat through built-up rust and chipped paint. Jobs that require sandpaper this coarse will require finishing with finer sandpaper.
Medium Grit Sandpaper
Medium grit sandpapers fall between 60 and 80. Use medium grit sandpaper for unfinished wooden surfaces such as furniture, shelves, trim and molding. For these projects, use multiple sanding steps to create a smooth and scratch-free surface for applying paint or stain. Start by using medium grit sandpapers from the low range with heavy pressure and then finish the project with a higher-range medium grit sandpaper, applying only light pressure.
High Grit Sandpaper
High grit ratings, known as fine or very fine, begin at 100 and may go all the way up to 1,000. Use dry 100 grit sandpaper for light hand sanding of most woodworking projects. Super-smooth finish work on metals, fiberglass and plastic requires very high grit numbers of at least 300. When preparing most metal surfaces for painting, begin with 100 grit and work up to 220 grit wet sandpaper.