Board Thread:General Discussion/@comment-24440536-20151028143002/@comment-25370154-20151029110010

You can use a brush. Of course, make sure to pick one good for such work (any modelism shop should have plenty of them).

The Airbrush is used to paint the whole model, which makes it useless for special paint schemes like Scarface 1 or anything like that. BUT, it can be useful to apply a colorless protective layer.