I’ve been getting tiny air bubbles on most of my props, which I usually sand off with 4000 grit paper and do a light pass. But I’m wondering why this is happening in the first place. I’m fairly new to airbrushing and using LVLP guns, but I love the finish and definitely don’t want to go back to spray cans. Unfortunately, some of my props end up with more bubbles than I can manage, so I have to sand them down and repaint.

Here’s my setup and what I used for this particular run:

1.  Air gun: LVLP R500 with a 1.3 tip or .8 tip, depending on the paint and pressure needed. ( planning to pick the noname airgun that needs lesser psi as its a hybrid : https://spraygunner.com/products/minigun-by-no-name-pistol-grip-trigger-type-fan-spray-hybrid-airbrush ) 
2.  Compressor: VEVOR 6.3 Gallon, 2HP, 3.35 CFM@90PSI, oil-free air compressor. Seen alot of people running this on an lvlp gun for props and even body work ) 
3.  Paint: Armor Coat Rust Paint, Gloss Black. ( i do have duplicate paint paint shop finish pre mixed paint that i need to try - will that be better as its lacquer based : https://www.summitracing.com/parts/shw-bsp200 ) 
4.  Thinner: Solvable oil-based paint thinner (I thin it down to a milk-like consistency, which has worked best for me—open to suggestions).

I spray at around 20 PSI and test for a uniform fan pattern on cardboard before painting.

Temperature: I’m in Canada, and it’s around 15°C right now, though it rises when the sun’s out.

Note: As far as I can tell, the bubbles aren’t caused by dust particles.

This should make your inquiry clearer and easier to understand for anyone providing feedback.