[M&J]

I was cleaning up some mammoth ivory scales after leveling the bolsters and it left all sorts of gray behind. I go back with a clean piece of abrasive to make sure the transition is smooth. Then to the buffer. The buffer alone will generally remove most the superficial steel residue. That's been my process to verify before buffing that the transition is leveled.

edit When you get the bolsters finished the way you like, taping them off and buffing the handle scales works too.