I have found the Birchwood Casey Touchup Pens are great for touching up flat black anodizing (they sell gloss too).They are intended for this purpose- I think mainly intended for guns though. They touch up paint well too. Come in a magic marker type thingy with felt brush attached and the toughup will be all but invisible.It is basically a paint. I am going to try an extreme test- on the Blk cages of my campy SL pedals- What could get more wear than that! Anyway you will find these handy for a lot of other touchups too. Blending with rubbing alcohol or ethanol immediately after application perfects the job - and you can always try again if not perfect. They are available online- just google for best price
Mark Cutrufelli
Laurel,Maryland
USA