Cleaning brake lines

Gday all,
      removed all the brake lines off the MK2 RS today. Im replacing the flexibles with braided lines, but, how do you clean the solid fixed lines/pipes.They're pretyy grubby and may have even been painted silver at some stage.  Im thinking if they're made of copper then probably polishing them by hand with something like brite shine metal polish then spray brake cleaner down the insides to flush them all out ready for reinstalling and bleeding. Ideas?/
    cheers
           Shep