When I start painting a model I start with the paint nozzle closed and open it slowly to get the paint flowing. All is well until I stop for a few seconds and then I have to open the paint nozzle more and more everytime I stop. Sometimes I have to increase the p.s.i.witch is already enought. I clean the brush after every use. What could it be? rambo1…
Your brush may be clogging with paint chips that can get in the paint mix. (I assume you are thinning your paint aren’t you?) When I add my paint to the airbrush paint jar, I use a fine mesh screen that I purchased from micro mark that catches the very fine paint contaminents that find their way into the needle port and end up clogging the airbrush. You can also get a fine mesh screen that fits directly around the plastic pick up tube that also works well.
You need to completely disassemble the air brush and give it a through cleaning. Even if your spraying water based paints clean it with lacquer thinner or air brush cleaning solution. Invest in new O-rings seals etc. and reassemble. When ever you have any problem such as you’ve described cleaning is usually the solution. You should make it a habit to thoroughly clean your airbrush after every usage. It isn’t always necessary to change the seals or O-rings but it depends on their condition.
I experienced a similar problem when I first started using acrylic paints (after 30 years of using lacquer-based paints). I followed suggestions which I’d seen here about using alcohol as a thinner and experienced exactly the same symptoms. After consulting the paint manufacturer’s recommendations, (finally [banghead]) I switched to using distilled water as a thinner and have had no further problems, and also found the paint to spray well at their recommended pressure.
As mentioned, regardless of what type of paint you use, keeping your airbrush clean is crucial to good performance. While I still prefer lacquer-based paints, the very first thing that you should do after painting is clean the airbrush thoroughly, and that means dis-assembly. It’s not normally required to remove the O-rings or seals, although they will need to be replaced occasionally, but you should otherwise do a complete tear-down and cleaning. Even with a double action brush, a couple of minutes is all it takes.
Wayne
I do clean the brush after each use but I will use a mesh net on the paint bottel thanks for all the advice. rambo1…