Acrylic Polyurethane Primer German Panzer Grey (RAL 7021) 17ml Matt acrylic colours, water-based and especially formulated for airbrushing. The Model Air color range contains the most complete selection of the military colors used in recent history, including the colors of WWI, WWII and up to the present. Each color is based on extensive research by our experts of the existing and previous military references so as to offer the modeler the highest possible historical accuracy. Model Air is used directly or diluted with Vallejo Airbrush Thinner or Flow Improver. It is recommended to first prime the surface, and then apply Model Air in several layers. The colors dry very rapidly and form a homogenous paint film of extraordinary resistance while preserving even the smallest detail of the model. For airbrushing these colors, the compressor air pressure is recommended at 15 � 20 PSI or 0.5 to 1 kg. Model Air can of course also be applied with a brush. For correct airbrush maintenance we recommend using the Vallejo Airbrush Cleaner.Model Air is not flammable, and does not contain solvents.