You can polish an airbrush needle using your Dremel tool
Use the large felt pad, spin it in the Tripoli until its coated.
Hold the needle with the point toward you, hold the Dremel
in your right hand, ( you want the rotation to be with the
taper of the needle on the donward slope ) run Dremel
on low speed and using light pressure, stroke the needle.
Rotate the needle in your hand.
You can actually see the difference and your paint will flow
much smoother with very little if any build up.