One 1-oz bottle of Tru-Color Paint brand Matte Concrete paint.

Tru-Color Paint recommends a starting pressure of 25 psi for most airbrushes.  400 series paints are designed to be easily sprayable straight from the bottle.  If thinning of the paint is desired, use of TCP-15 thinner is recommended.  Tru-Color Matte Sprayable Paint dries to a flat finish.  Clean-up is easily achieved with acetone.