The solutions suggested by Ken will work very well but, although messy, rubbing the barrels down with W&D paper direct from black, is my preference. I start with 400 grade and finish with 800 and only use a heavier grade if I need to on specific scratches or marks. Lubricated with water (if you are certain of your ribs' integrity)or a very light lubricant such as WD40, you can see the scratches that need removing very clearly while the blacking remains within them. When no black lines remain, you can go to the polishing wheel for the final gloss.
BTW I do not do the wheel polish on damascus, nor often go finer than 400 grade as I suspect it seals the surface and makes it more difficult to get the browning started.
