The abrasive grains used in todays coated abrasives are Emery, Crocus, Garnet, Aluminum Oxide,Silicon Carbide and Zirconia Alumina. Emery, Crocus and Garnet are natural grains whereas Aluminum Oxide,Silicon Carbide and Zirconia Alumina are man-made synthetic grains. The newer synthetic grains are more common in typical coated abrasives because of their strength and durability, however natural grains, like Garnet, are still very popular with specialized craftsmen.
Within each type of backing there are numerous variations of strength and flexibility. In paper, for instance, the weights(unit of measure determine by the tensile strength) range from the lightest "A" weight to the heaviest "F" weight. The lighter weights are generally more flexible and are used for fine finish or detail sanding. The heavier weights are more durable and are used primarily in the coarser abrasive grains and for heavy machine applications. Cloth backings are typically used for belt sanding where durability and flexibility are required. Cloth is also commonly used in roll or disc form to clean or deburr metals. Abrasive mesh is a variation of a cloth backing where the cloth fibers are woven into a mesh pattern. Mesh, or screen, when coated with abrasive grains leave openings which allow the abraded materials to pass through the mesh instead of loading up the abrasive surface. This limits the negative effects of loading on the life of the product.
The adhesive that is used to adhere the grains onto the backings are either animal hide or bone-based glues or various types of resin adhesives. Depending upon whether there will be heat generated or whether the abrasive will be used in or near moisture usually determines which type of adhesive to use. Resin glues are also generally preferred where longer life of the abrasive product is desired.
Coated abrasives take many shapes depending upon the particular use of the sanding product. Rolls, sheets, discs and belts are available in a variety of sizes and configurations to fit individual hand or machine sanders.
