Measure of the roughness of sanding belts and similar abrasives; The roughness of abrasives depends on the grain size of the abrasive particles, with which the backing material made of paper or textile is coated.

It is given in mesh, i.e. how many meshes a sieve has on one inch (25,4 mm) length. The mesh size of the sieve determines the size of the abrasive particles. The larger the number, the finer are the abrasive particles and the smoother is the sanded surface.

Alternative terms

• Paper graining