Which type of sandpaper will work best for a particular job?

One way to determine which sandpaper will work best for a particular job is to know the abrasive materials and their properties.

Some papers use natural abrasives:

• Garnet is good for hand-sanding. It works well on raw wood, removing light scratches and preparing the surface for finishing. The abrasive particles break during use, providing new edges for removing material but garnet sandpaper wears quickly. 

• Emery works for both hand-sanding and power-sanding metal. Use coarse grits to remove rust or paint, and finer grits to polish. Emery cloth sandpaper has a cloth backing.

Other abrasives are man-made:

• Aluminum oxide is a common sandpaper type that works on wood, plastic, metal and drywall. The particles break during sanding, constantly exposing new, sharp edges. Aluminum oxide sandpaper is long-lasting, making it a popular choice for power-sanding, and you can also use it for hand-sanding.

• Silicon carbide sandpaper removes material more quickly than aluminum oxide but doesn't last as long. Use it on wood, plastic and metal for tasks such as rough-sanding, removing paint or rust, and sanding between coats when finishing. Use it on drywall to smooth joints. Silicon carbide products often have a waterproof backing that you can use for wet-sanding, which is a good technique for minimizing scratches when applying liquid to lubricate the work surface. Wet-sanding also helps to prevent the sandpaper from clogging with dust, remove loose abrasive particles and reduce airborne dust.

• Zirconia alumina is suitable for wood, fiberglass, metal and painted surfaces. You'll find it in the form of belts, pads and discs for power-sanding. Like garnet and aluminum oxide abrasives, the particles break during use, maintaining sharp edges that remove material quickly. Zirconia alumina lasts longer than aluminum oxide.

• Ceramic alumina is available in belts and discs for power-sanding and is good for aggressive material removal on wood. Ceramic abrasives are durable, lasting longer than aluminum oxide.

You may see sandpaper labeled closed coat or open coat. Closed-coat products feature abrasives covering all of the backing. This construction removes more material — making it effective for hand-sanding — but can clog more quickly than open-coat products. Open-coat products have empty space on the backing, giving waste material room to accumulate without reducing performance. Since they don't clog as quickly, they're effective for an electric sander.