Advice on spraying white enamel

i totally agree! i hate spraying yellow N white.

Thanks for the advice guys. I'm going to start with flat white thinned about 50% (Testors airbrush thinner)then a lot of coats of insignia white. I usually spray at between 10 and 20 psi. I'll post the results in the aircraft forum.

A good primer, wet sanding and many light coats. White and yellow are killer colors to paint. I use Tamiya AS-12 Aircraft Silver as a primer and then, like Gerald, use Flat White as my first coat. Thin lots and put on lots of very light coats.

Many light coats...

I find that when I need to apply white as a color I start with a base of flat white first. The flat white acts as a good primer base for the gloss. Once the flat white has cured I apply the gloss in several light coats until I have the consistency of coverage and gloss effect I want.

Rough vs runny is not a color issue. It is just that white highlights roughness or runs.  It is likely the problem is one of several issues: thinning ratio, distance from model, or pressure.  Further, these are related.  Changing the thinner ratio can be compensated for by adjusting distance.  I personally use 15 psi for gloss paints, 20 for flats.  I know people who use other pressures but find many airbrush novices start too high.

The primary problem that is truly a white paint issue is coverage. Yellow is even worse.  I find I have to use more coats or a thicker coat with these- also a good primer is almost essential with these colors.