airbrush help needed

Hey gang,
This is my first time with a dual action action airbrush and I'm
having some problems. My brush is a Badger 150 and I'm Gunze aqueous
colors. My problem is I'm getting a a kind of spatter effect every so
often. By spatter I mean, it's not a big snot of paint flies out but
rather what appears to be water or thinner with very little pigment. My
brush will be going along fine and then out comes the clearish liquid
with little pigment. I've thinned the paint down to about 50/50 with
Gunze aqueous thinner and I think my brush is pretty clean as it is
disassembled after each use. I'm running about 20-25 psi from my
compressor. Any help on this matter would be greatly appreciated.
Thanks,
Gene DiGennaro
Baltimore, Md.