I've never used an air brush before, but I see it's the way to go to paint (DPM) structures. So, I purchased a single action air brush from Harbor Fright and have played with it on some cardboard. The problem I'm having is the paint seems to be too thick to flow out of the airbrush correctly. I'm using acrylic paints I got at a local crafts store. I 've used this paint before with a regular brush and it went on great. What is the correct paint to thinner mixture? I'm using Windex as a thinner, it seem to mix better then water.