Getting surface bubbles using MM clear enamel.

Hi folks,

I'm new to modeling and airbrushing. I've tried to read as much as possible, but there is nothing like experience that comes with time, trial and error, etc.

I have a Paasche H set that I've used to paint a custom 3D model that has been sanded, primed and finish sanded with 1500. I used MM enamel for the paint and it turned out pretty well with no problems. Driving the H set is a 29gal compressor with a regulator/drain and an inline desiccant trap. The regulator gauge is set to 18 psi, but drops to 15psi when painting. I thinned the MM clear coat with Testors enamel thinner at approximately 50/50... well, probably closer to 55/45 clear to thinner.

It has now come time to apply the clear coat. However, I'm now getting some stray bubbles when test painting a couple of samples that were finished in the same manner as the 3D model. After I finished, it dawned on me that my Paasche booth still had the old paper from the original painting sessions and I guess it's possible that some dust could have been kicked up?

That said, are there any special tricks when it comes to spraying clear vs color?

Thanks in advance!