Scary sharp is a method of sharpening that uses the sandpaper in place of the traditional oilstone or waterstone. Sandpaper can be any sanding sheet. The abrasive paper is fastened to a support rigid and flat to create the surface of sharpening. Normally use a sheet of glass, but also marble, plywood, MDF will produce satisfactory results. The fixing method is normally a matter of user preference, and may include water (by means of surface tension), removable spray adhesive or simply by using double-sided adhesive tape. The most obvious benefit of the Scary Sharp system are speed and cost. Anyone with sandpaper and a reasonably flat surface can sharpen any cutting tool with good results. Unlike traditional stones, no maintenance is necessary because the surface of grinding does not deform or consumes creating the typical depression of the stones. Compared to the stones, also, the sandpaper is lower in terms of costs. A series of increasingly finer grits will produce perfect sharpness. Here we propose the finishing sheets as for roughing you can use the standard sandpaper found in the section Abrasives - SIA.
Scary sharp on Wikipedia