Stearated sandpaper is also known as self-lubricating sandpaper. It is used primarily for sanding wood and paint finishes as well as metal. The applied lubricant or soap prevents clogging and extends the life of the sandpaper.
Aluminum Oxide Sandpaper
The most common type of sandpaper--aluminum oxide--is useful as an all-around sanding paper. Appropriate for unfinished wood and metal, this type lasts longer than other abrasives. Stearated aluminum oxide sandpaper is available but not the most widely used.
Silicon Carbide Sandpaper
Though aluminum oxide is the more commonly used abrasive for sandpaper, silicon carbide is used on some types of paper for smoothing wood finishes and the sanding of metal. Stearated sandpaper is most often of the silicon carbide type.
Often made of a metallic soap, the stearate is a dry lubricant applied to the surface of the paper, filling in the space been the grains. The application of the stearate prolongs the life and use of the paper, preventing the sanded material from clogging the areas between grains.