couple questions about using a compressor with an airbrush

[EL PARRo]

First, how many psi should I have when airbrushing? Second, I've heard people mention something called a "moisture trap." How important is using one when I airbrush and what exactly does it do?

thanks in advance

[chutton01]

OK, a general rule is 10-15psi for acrylics, 20-25 psi range for enamels. Of course, this is general painting, and if you are doing weathering or oversprays or other special effects, you need to experiment (I think lowering the pressure gives a 'grainier' effect, which could be useful for weathering or painting rough surfaces like stone or concrete)

Moisture traps, as you would expect, remove water from the incoming air supply (it comes from from the compressor). I believe it is quite important to have, as it helps prevent water from mixing with the paint and so ruining the finish.

[Anonymous]

MR, in their painting video and in "Basic Painting and Weathering" recommend 15-25 psi for acrylics and 15-20 psi for solvent-based paints. I've had my best results using 20-25 psi with Polly Scale acrylic paints.

[Virginian]

Moisture trap depends on the compressor setup and environmental conditions. Rather than write a book, I'd just advise you to get one.

[Anonymous]

As mentioned, a moisture trap captures water in the air line. If water gets into your air line, you get it sprayed onto the model you are trying to paint. In the past I've had some water on my models when using lacquer based paint - it messes things up! Since then I've gotten a moisture trap and haven't had any problems. Don't know what the water would do on acrylic paints, but probably nothing good.

The moisture trap is an in line filter. You normally have to cut your air hose to insert it. Mine is made by Paasche, but there are many others. Cheap insurance!

As to air pressures, a lot depends upon your spraying outfit. When acrylics first came out it was recommended that at least 30 PSI be used, as they were not intended to be thinned before use. I found that I more or less had to test paint for spraying, as the consistancy of the paint was not always the same. Some would spray OK at lower pressures, others needed much more just to get out of the airbrush. Experiment and you will find what you need.

Bob Boudreau