What is the difference between sandpaper grits?

All types of Sandpaper have many sharp edges that cut away at whatever you are sanding, wood, metal, drywall compound and other items.

These abrasive edges are glued onto various backing materials such as Kraft paper with a special bonding agent. Different grades of sandpaper represent the difference in quality of the abrasives, the backing material and the bonding agents.

Sandpaper that is Industrial grade uses higher quality materials than commercial grade sandpaper but is only available in specialty shops.

Sandpaper is measured by its grit size, or number of sharp particles per square inch of sandpaper. The larger the grit size, the more edges there are and the smoother the sandpaper is. The density of the grit will make a difference as well. Open-coated sandpaper has gaps between the grits, allowing sawdust to gather between them so it does not interfere with the sanding process. Closed coated sandpaper on the other hand does not have those open spaces.

You need to choose the grit size of sandpaper depending on the job you are trying to do.

You will need coarse sandpaper that is 40 to 60 grit for heavy sanding and stripping. If you want to smooth surfaces and remove small imperfections, 80 to 120 grit sandpaper should do the job. A super fine 320 to 600 grit sandpaper is used for finishing surfaces smoothly. Some applications will require even greater grit. In the automotive industry you come across high grit sandpaper that is used to polish clear coat.

Ever heard the term “go through the grits.”? There is a meaning to the saying. It 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 will remove the scratches from the previous layer.

There are four main types of sandpaper grits. They are garnet, silicon carbide, aluminum oxide and ceramic.

Garnet will wear out the fastest but provides the benefit of creating the smoothest surface. Silicon carbide is good for sanding hard materials such as metals and plastic. Ceramic sandpaper, which is the most expensive and roughest grit, is used for shaping wood. So if you want to make a sphere out of a square block, you should use ceramic paper. Aluminum oxide lasts longer than the other kinds of grits of sandpaper since it contains a self renewing property. But because it is the most delicate, it crumbles easily, forming new soft edges.