by Wayne Morris
Airbrushes “spitting” while you’re painting can be very frustrating, particularly if it defaces the paint already on the model. Someone once asked how to solve this. Here’s the gist of his problem of the spitting airbrush: “It was suggested that condensation from the air line caused by the humidity in the air was causing the spitting. So I bought a moisture trap, put it on the line, and that seemed to help for a while. But when I changed colors (cleaning the airbrush in between), the sputtering-clear was back. This seemed to me a clear (no pun intended) indication that it was thinner, in this case from the recent cleaning.”
To me, that sure sounds like it’s thinner trapped in the airbrush after cleaning. You need to make sure the thinner is evaporated and/or blown out of the airbrush before using it again. After cleaning, just keep operating the airbrush without anything in it to make sure that it’s drained dry. Also, cover the nozzle with your finger or a tissue while pushing the trigger down. This blocks the airflow so that air is forced back through the paint path.
Another remote possibility: Do you mix the paint & thinner in the airbrush cup. If you mix them in the cup, they might not be getting mixed thoroughly.
Sometimes spitting occurs when there’s little or no paint left in the cup. That suggests a possible problem in technique: Don’t try to paint until the cup’s empty, as the last bit of paint will tend to spit out of the airbrush unevenly when it starts sucking in air along with the paint; sort of like slurping the last bit of a drink through a straw. Instead, refill the paint cup before it drops below the opening of the siphon tube. Don’t try to spray out the last few drops of paint while the airbrush is pointed at a model.