Preventing The Runs...

Runs are generally cuased by too heavy an application.  Just doing light coats to build up a base should prevent any running.

What you might be more concerned about is spattering or spitting paint, where paint that has built up on the tip is suddenly spit on to the surface of the model. 

There are a few things you can do.  First is to make sure that your paint is properly thinned and stirred.  Next what you can do is keep a post-it note handy.  Hold the post-it a few inches away from the surface of the model, but next to where you'll be painting.  Start spraying on the post-it, then move to the model.  The post-it should catch the spatter.  If you don't have a post-it, try blowing any loose paint out the tip by pressing down on the trigger, but not pulling back.  I can't guarantee that you still won't get spatter, but it should help reduce it.  If you still get spatter, the next few light coats should cover it up.  If it's kind of heavy, use the corner of a paper towel or a q-tip to wipe up the heavy stuff before continuing to paint.

Hope that helps some.

-Fred

Circuitrider wrote:

But how do you prevent runs and/or spatters when you must start on the model surface? Low presure, thin paint...or what?  Any ideas? I should add that I use a double action Aztek and a compressor with a regulator.

When I used an Aztek A430, I used to get the same spatter problem that you described.  What seemed to be happening was that paint would collect on the little needle guards on the tip, so when I would start spraying, the air would periodically blow it off and spatter.  The best solution I came up with was to keep a paper towel handy so that I could touch it to the tip and wick away the paint droplets.

Andy