I also use polish but combine it with steel wool. 000 steel wool with WD-40 and it can really dig deep and get out some fairly deep black, but it does leave a bit of a scratchy finish, so 0000 with polish can really makes a nice semigloss finish. It does require quite a bit of elbow grease but is a low tech low risk way of getting all the black and red rust off and the blade shiny.