The Army Painter: Warpaints Airbrush Medium. The Army Painter has developed The Warpaints: Airbrush Medium to enable our superior quality Warpaints to be used with an airbrush. The Airbrush Medium is highly versatile, and any high-quality acrylic paint will benefit from it. A real quality of this product is that the Airbrush Medium not only works as a thinner for acrylic paints - but also as a flow improver!