All About Abrasives
Once, sandpaper came in two colors: black or tan. In recent years, manufacturers have begun to tint their abrasives with dyes of lilac, teal, or burnt umber to make them stand out from the competition. Now only the natural abrasives — garnet and emery — can be counted on to always display their true colors. Following is a guide to the six most common types.

Natural:
Garnet
Suitable for sanding bare wood. Dulls quickly compared with man-made abrasives.

Emery
Excellent for sanding or polishing metal; too soft for other uses. Comes on flexible cloth backing.

Man-Made:
Silicon carbide
Extremely hard; sharp enough to cut glass, but wears quickly. Best for smoothing joint compound and removing dust nibs between coats of finish. Extra-fine grits are used for wet sanding the final finish coat.

Aluminum oxide
The jack-of-all-trades abrasive; great for hand or power sanding on wood, paint, or metal. Not as sharp as silicon carbide, but lasts longer.

Ceramic
Tougher, more durable, and more expensive than other abrasives; often bonded chemically with aluminum oxide. Used primarily on belts and discs for power sanding.

Alumina zirconia
An alloy of aluminum oxide and zirconium oxide. Sharp, hard, and durable, it cuts faster and lasts longer than aluminum oxide, but isn't as long-lived as ceramic. Found mostly on belts and discs for machine sanding.

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