Sandpaper

Sandpaper is a form of paper where an abrasive material has been fixed to its surface; it is part of the "coated abrasives" family of abrasive products. It is used to remove small amounts of material from surfaces, either to make them smoother (painting and wood finishing), to remove a layer of material (e.g. old paint), or sometimes to make the surface rougher (e.g. as a preparation to gluing).

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

There are countless varieties of sandpaper, with variations in the paper or backing, the material used for the grit, grit size, and the bond.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Backing

In addition to paper, backing for sandpaper includes cloth (cotton, polyester, rayon), polyester film (Mylar), and "Fibre". Cloth backing is used for sanding discs and belts, while mylar is used with extremely fine grits. Fibre or vulcanized fibre is a strong backing material consisting of many layers of impregnated paper made from rags. The weight of the backing is usually designated by a letter. For paper, the letters range from A to F, with A being the lightest and F the heaviest. Letter nomenclature is different for cloth, with the weight of the backing being, from lightest to heaviest: J, X, Y , T and M.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Material

Materials used for the abrading particles are:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• flint — no longer commonly used;
• garnet — commonly used in woodworking;
• emery — commonly used to abrade or polish metal;
• aluminium oxide — perhaps most common in widest variety of grits;
• silicon carbide — used in microgrits, especially for wet-and-dry sandpaper;
• Alumina-zirconia — (an aluminium oxide - Zirconium oxide alloy), used in very fine (microgrit) papers;
• chromium oxide — used in extremely fine (micron level grit) papers

As well, sandpaper may be "stearated" where a dry lubricant is loaded to the abrasive. Stearated papers are useful in sanding coats of finish and paint as the stearate soap prevents clogging and increases the useful life of the sandpaper.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Bonds

Different adhesives are used to bond the abrasive to the paper. Hide glue is still used, but this paper is not waterproof. Waterproof or wet/dry sandpapers use a resin and a waterproof backing such as cloth.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Sandpapers can also be open coat, where the particles are separated from each other and the sandpaper is more flexible. This helps prevent clogging of the sandpaper.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Shapes

Sandpaper comes in a number of different shapes and sizes.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• sheet — usually 9 by 11 inches, but other sizes may be available
• belt — usually cloth backed, comes in different sizes to fit different belt sanders.
• disk — made to fit different models of disc and random orbit sanders. May be perforated for some models of sanders. Attachment includes Pressure sensitive adhesive (PSA) and "hook-and-loop" (similar to velcro).
• rolls

Paper: Paper is a thin, flat material produced by the compression of fibres. The fibres used are usually natural and based upon cellulose. The most common material is wood pulp from pulpwood (largely softwood) trees such as spruces, but other vegetable fibre materials including cotton, linen, and hemp may ...

Abrasive: An abrasive is usually a material that is used to smooth or to machine another softer material through extensive rubbing. Some common examples of abrasive objects are:...

Coated abrasives: Coated abrasives are made of abrasive grains adhered to the surface of flexible or semi-flexible backings such as...