tip dry?

I've been experimenting with some acrylic paint lately, and here's what I've done.  I spead some paint in a small saucer and let it dry.  Then I dipped a Q-tip in various liquids (new Q-tip each time) and swabbed a small spot lightly to see how well they would dissolve the paint.  I tried different spray cleaners and solvents. The best results seemed to be lacquer thinner, isopropyl alcohol, and Mr. Clean Multi-Purpose spray.  I've read that a lot of people use Windex with ammonia.  It worked, but not quite as well.  Why don't you try your own tests.

The main thing is to clean or flush out your brush right away, before the paint has a chance to begin drying. 

By the way, I always swab out the paint path in my brush after each use anyway.  I'm a bit anal about keeping it clean. 

Don 

I have the same problem when using water based acrylic paints.  Seems the internal workings get gummed up.  I've heard some use Simple Green to clean the airbrush and even a little when spraying.  I've thinned Future with Simple Green and got great results. 

I haven't tried to use Simple Green with paints, however, I think it would work, and probably keep the airbrush cleaner.