Airbrushed acrylic wash beading up - advice?

[ChrisBcritter]

I'm trying to get a dirty grey/brown wash over flat black lacquer. I thinned Testor's acrylic weathering colors down about 4:1 with their Aztek universal  thinner and airbrushed it on a scrap part that had been sprayed flat black. Ta-da! Beaded up like crazy. Tried adding a little rubbing alcohol and... beaded up again. Any suggestions? Normally I'd brush the stuff on but I don't want brush strokes. Thanks for any help you can suggest!

[Snake45]

What I like for what you're doing is to start with bottled Testor Dullcote, then add just a little tan and a little medium gray. Thin with lacquer thinner. Airbrush from about a foot out. When you get where you think you need just one more coat, STOP. Let it dry, take a look and see if you want any more. You probably won't. This makes a very convincing and EASY under-chassis weathering. 

I realize you're trying to do this with acrylics, but I have no experience with them. If you can airbrush lacquer, this will work for you. 

[dmthamade]

try adding a drop of dishwashing soap, breaks the surface tension of the wash.

 

HTH don

[bisc63]

Washes tend to work better over glossy, smooth finishes. I'd seal with a gloss coat, wash, and then dull coat.

[ChrisBcritter]

Took another whack at it a while ago. This time thinned it about 2:1 with a small drop of dishwashing liquid. Success! Nice subtle dirty effect and no beading. Thanks for the suggestions!