One 1-oz bottle of Tru-Color Paint brand Flat Brushable Rust paint.
Tru-Color Paint recommends a starting pressure of 25 psi for most airbrushes. 800 series paints are designed to also be easily brushable. If thinning of the paint is desired, use of TCP-15 thinner is recommended. Tru-Color Flat Brushable Paint dries to a flat finish. Clean-up is easily achieved with acetone.