Janelle,
"polishing mops" are not a good choice for polishing SS prints that have not first gone through an initial surface treatment, like "barrel tumbling"! This material is
extremely hard, like tool steel. It is also
extremely abrasive! Until the (as printed) surface or,
bark is cut down, it will tear up any cotton wheels, mops or felt bobs that you have. Also know that in this relatively rough state, small parts tend to snag, very aggressively! So be careful if you still want to give it a try. Here are a few suggestions:
Carbide burrs and diamond based abrasives are the quickest and most economical way to cut, smooth, brighten, or polish printed SS parts! Some types of rubberized abrasive wheels and "non-woven" style abrasive pads and belts are also useful but not as effective as carbide & diamond. Carbide burrs can do deep cutting or just brighten surfaces. Diamond products come as wheels, burrs, hand files, lapping pastes and film backed papers. These are available from relatively coarse cutting, down to optical grades. The "import grade" of most diamond products is low in cost and they work very well in most applications. Higher grade materials cost more, but because they work so quickly and effectively they come out costing less than any material I have found.
I say all this after many years of trying just about every method and abrasive product available. Just be safe and have fun.
-G