Acura advises that brake discs that are FNC treated are never to be refinished.
FNC (ferritic nitrocarburizing) brake discs are treated with a surface-hardening process that helps to reduce disc wear and increase corrosion resistance.
FNC brake discs are marked with the letters FNC. If you see these letters, do not resurface the discs on a brake lathe, as this will remove the FNC treatment.
If a brake disc is out of runout specification, replace the disc.