i took woodworking in high school and we used watersanding to do finishes mostly. The water is supposed to remove all the little particles that u cut off while sanding. normal sanding produces dust, water sanding keeps the dust from getting in to the air, catching it in the water. the water also serves to reduce the heat created by the friction between the sandpaper and the metal. when we were doing finishes on guitars adn everything else we made in shop, we only went up to 1000, anythign about that is just rediculous. like other people have said, the point of the slow progression of sandpapers is to keep reducing the size of the scratches. if u start on 200, which is probably too corse for metal, the 300 should be used til the scratches created with the 200 are gone, then 400 till the 300's r gone, etc. using 1000 to remove scratches created using even 400 sand paper is way to time consuming.
