Scotchbrite wouldn't work on 2-rail. Our guard rails and switch points would just hook it, and cause a crash.
I built a brass drop-center flat, forgot to put floorboards on it, and made things to ride in the low rectangular openings. One side is a sanding block with 320 wet-or-dry paper; the other is a roller with a piece of cloth fastened to it.
I saturate the roller with Wahl clipper oil, hook the thing in a freight train, and let it roll. Photo later.