If you have to have a smooth surface get an angle grinder and use flap wheels to smooth it down. Start with a reasonably coarse wheel and go toward finer grits. If you have a square type pan you'll need to get one of those little triangular type sanders to do the corners. I do like the smooth pans better than the rough ones but not enough to go to the trouble to smooth them out. Pizza pans don't need to be near as smooth as frying pans intended for eggs and the like.