Help with airbrushing model cars

[Gamaliel]

I keep getting tiny pimple-like flaws that look like I painted over a tiny, and I mean real tiny grain of sand. I moved my spray booth to a bedroom that has humidity between 35% and 50%. I have used numerous primers. My favorites are Mr. Surfacer 1500 and Tamiya Fine Surfacer. I've used 6 different airbrushes and tip sizes. I'm currently using a Harder and Steenbeck Evolution with a 4.4 tip. I've used Mr. Color lacquers,
MCW enamels and lacquers and Scale Finishes enamels. I've thinned to various ratios with Mr. Color Leveling Thinner and also used lacquer thinner. All with the same result. The finishes all look great except for these tiny dots. I can sand them out and polish but that's pretty tedious. Anyone know what the problem is or have any suggestions for possible solutions? I should also mention I painted one model with Tamiya TS paint in a rattle can which came out perfect. I don't get it.

Thanks,
Rick

 

[TimM63]

I would try wiping the plastic with degreaser or alcohol before painting. Also try painting without primer. A .44 tip should spray a nice coat. Try several very light coats.
What psi are you spraying with?

 

[BarleyBop]

Welcome to the Addict!

 

[Gamaliel]

18-20 psi