Ann,
Try a wool applicator with Gum Tragacanth from Tandy Leather # 2264-01 and then rub the edge with a hardwood or plastic edger, bone works too. This is the modern equal to human spit which is what the old timers used - it breaks down the fibers and leaves a very nice smooth edge. Be careful using your plastic edger in a drill, I have burned the edge and melted my edger by go too slow with it, this does work work real nice for doing long belts and such. Good Luck, Morgan