You know it was bound to happen. I just finished airbrushing several undecorated freight cars. I used Folk Art by Plaid paint thinned with windshield washer fluid. The airbrushing went great. Very little problems with clogging. The paint went on smooth and covered well. Thanks for all the previous recommendations I received. Now for the question. I gave each car an a coat of light gray to act as an undercoat. The cars were originally black. The final colors will be oxide red, red, blue, and/or black. The question is should I seal the paint that I just applied? If I seal it will it cause any problems with adding additional coats?