Sandpapers are essential to creating a smooth surface on which to apply finish. Usage information is here.
Silicon Carbide Sandpaper
Silicone carbide sandpaper is often a dark gray or black color and usually can be used either web or dry. Use it on acrylics wet and on woods dry. This type of sandpaper is used for sanding automobile finishes, and is available in grits up to 2000. It can be used wet or dry and can be washed off and re-used.
Aluminum Oxide Sandpaper
This is the most common form of sandpaper known to all woodworkers. It is usually a light brown or beige color. It is often coated with a stearate compound to prevent the sanding dust from sticking to the sandpaper. The compound may interfere with some finishes. It always has a paper backing and must be used dry.
Micro-Mesh (MM) is a brand of abrasive that many pen makers have come to rely on, The format of MM that pen makers use most frequently is a cloth backed product with a latex cushioning layer embedded with silicone carbide crystals. The grit size of MM is in the extra fine to ultra fine range of abrasives with crystals ranging in size from 30 microns down to 3 microns.
MM uses a different grade scale than standard sand paper. The conventional format of MM comes in 9 grades as follows: 1500, 1800, 2400, 3200, 3600, 4000, 6000, 8000 and 12000. The MM 1500 grade has a grit size that is roughly equivalent to a 350 grit in a standard sand paper. But beacause of the latex cushioning layer of the MM, the 1500 grade of MM will produce a much finer, more uniform finish than the 350 grit of regular sandpaper.
MM is expensive in comparison with regular sandpaper but it lasts much longer. MM can be used either wet or dry and can be washed and dried and reused hundreds of times.