Like Mike V, I too favor Tamiya over MM Acryl. I had the same thing happen when I tried repeatedly (and with varying formulas) to airbrush even the modest of fine lines with MM Acryl. I just couldn't get it to happen with those paints. I shot fine lines with Gunze, Polly Scale, Xtracrylix and even thinned artist acrylics with ease! Then I tried the Tamiya, thinned it with common denatured alcohol and presto!, the perfect (almost) paint. The only thing lacking in my opinion about Tamiya acrylics is there limited color range, but Urban Fredrickson's color mixing chart solved this issue as well. It can be found here. Thinning, airbrushing and adhesion was superb. Been using them for going on two years now with consistantly great results.
Here's my 1/72nd scale F-111F airbrushed with thinned Tamiya acrylics. I shot fines lines to achieve the tight feathered demarcation for the camouflage.
Greg Williams
Owner/ Manager
Modern Hobbies LLC
Indianapolis, IN.
IPMS #44084