I've borrowed one technique from the old Niedner process, using a small .0025" wheel. After a curing soak in water displacing oil (I use 50/50 used motor oil and kerosine) the finish is really dark and tough, so I go over the tubes with the wheel, using clear mineral oil. It really improves the finish. That's the last step for fluid steel tubes, but only the first of several steps for polishing Damascus and Twist. Just make sure you mark the wheel as an "Oil Wheel" so you don't use it for regular carding.
