I've used Testors Acryl line before in single paint color schemes without much trouble. I'm trying to do fine-line work with it and I'm not having any luck at all with it. I've been using the Testors Acryl airbrush thinner and even added some liqutex arylic retartant to the paint and I'm having the same problems, which is that when spraying a fine line, I keep getting spitting and a build up of dried paint on the tip of the airbrush that I need to clean off. I've tried my Tamiya Super Fine airbrush and my Iwata HPC-BCS brush which has a larger needle and both are producing the same results. Anyone have any other suggestions?

I have had this problem to, several times..Whats is our air pressure setting?, try to go low, like 12 psi. I deal with it by airbrushing in one hand a a q-tip in the other, stop and clean as it builds...

To help keep the tip clean, try using a light coat of needle lube on the needle. Also, if you can , reduce your pressure down to at least 10 psi, this can help because it allows you to maximize your needle opening. Also, go with at least a 50 50 paint to thinner ratio although usually you can spray MM Acryl right out of the bottle. As was previously stated, you might just have to keep a swab handy and clean the tip of needle often.