Hi Vincent, Don't know if I'm telling you about the right things or
not, but, we used Scotch Stones (Scotch Hones??) to take the image
off of aluminum Lithography Plates!
They were a very hard stone about 1/4" square and about 6" long and
used like an eraser! They are still available, used like an abrasive
on metals! If this isn't what you were looking for I'm sorry to give
you a bum steer! Jim