sandpapper

Sandpapper, or sandpaper, is a coated abrasive used to smooth, shape, or finish surfaces by abrasion. It consists of abrasive grains bonded to a backing material such as paper, cloth, or film. The grains are held in place by a resin or glue binder, and the assembly is designed to be used by hand or with power tools. Common abrasive materials include aluminum oxide, silicon carbide, and garnet, each offering different hardness and durability. Backings vary from lightweight paper to durable cloth and flexible film, with some products being waterproof for wet sanding.

Coated abrasives are produced in various coat types and grits. Open coat sandpapers have gaps between grains to reduce loading and improve cooling, while closed coat sandpapers have grains covering most of the surface for a finer finish. Grit size indicates the abrasive particle size; lower numbers are coarser, higher numbers finer. Grits are standardized in scales such as FEPA (P grades) or CAMI (A grades). Typical ranges: coarse 40–60 for rapid material removal; 80–120 for initial smoothing; 180–320 for wood finishing; 400–600 for very smooth surfaces; 800–2000 for polishing or final finishes. Waterproof or wet/dry variants allow use with water or lubricants to reduce heat and clogging.

Uses and techniques vary by material. Sandpaper is widely used in woodworking, metal finishing, plastic shaping, and automotive bodywork. It can be used by hand or with belts, discs, or orbital sanders. Proper technique involves using appropriate grit, maintaining a consistent pattern, and avoiding excessive pressure to prevent gouging or heat damage. Safety measures include eye protection and a dust mask or respirator to limit inhalation of sanding dust.