Model Master Acrylic

Lacquer thinner'll clean paint from brushes, though.  I use it on my brushes if I get paint built up in ferrule.  But I agree about thinning.  I use lacquer thinner to thin lacquers, and Tamiya flat acrylics, sometimes, because it'll produce an absolutely flat finish.

I tried once to revive a bottle of Testor's gloss enamel with some lacquer thinner, and yep, it turned to cottage cheese in the jar.

Only 2 things are thinned by lacquer thinners, Lacquer paint and tamiya acrylics. it will ruin anything else.

I have posted a thread here about airbrushing acrylics to help you understand better:

http://cs.finescale.com/fsm/tools_techniques_and_reference_materials/f/18/t/176364.aspx

The big problem with acrylics, in my experience, is that each requires its own brand of thinner. Period. Ther is truly no such thing as a "universal" acrylic thinner... in spite of the Testors product name. Flat out, if you want good results with a particular brand of acrylic paint, use their brand of thinner. Anything else is "good luck". Each brand of acrylics has different formulation for their carrier, so what works with one brand, thinning for airbrushing, can cause diasaster in your airbrush with another brand.

Even generic hardware store lacquer thinner, which can thin pretty much most anything, may not work with a particular brand of acrylic paints. 

Now as as far as Testors Model Master acrylic paints go, for the most part, in the words of a song from my youth... "barf out, gag me with a spoon..." 

I play it safe by using the same thinner for acrylics from the same company as the paint I am using.   I know I maybe paying more but I don't want to suffer the same issue you just experienced.

The short answer to your question...I tried what was quickly available at the LHS and gave it a shot given limited (read: no) airbrushing experience.  Thanks for the advice, I'll run some testors universal down and use it with MM from here on, assuming good results which I have no doubt will be the case.

I'll be the first to admit my experience with airbrushing has largely been trial and error up to now.  Thankfully I found this forum that is usually quick with better answers than the Google box has managed to turn up!

Why are you using lacquer thinner or Tamiya brand thinner when you coud have used Testors brand Universal thinner to save yourself the trouble?  No wonder you're having issues with paint gumming up. 

I use Testors brand Universal thinner when using Model Master acrylics. The trouble with switching to Tamiya exclusively is the limited range of colors as opposed to Model Master acrylics or any other brand paints.