Great work there Glenn.
Regarding the 'spitting' with the airbrush, this can be due to a number of things - thinning, where a tiny piece of paint pigment hasn't 'dissolved' into the thinner, causing a minute blockage; a slippage of the needle clutch, causing the needle to 'slide' as the trigger is activated; partially blocked or dirty venturi or jet nozzle, not always immediately obvious; tiny deformation of the tip of the needle; dried paint build up on the needle, again not always immediately obvious; worn or slightly displaced 'o' ring seals.
Additionally, and this should be more obvious, if the compressor is pulsing, that can cause uncontrollable 'spitting'.