Air Compressors

Water separators do just that, separate the water from the air. If you don't drain the water, it can get full and contaminate your air supply. Some makes have a service life as well, and need to be replaced.

I use a separator at the compressor, one at the spray booth where I have my regulator mounted, and a third inline type about 3' from the airbrush.

Make sure your separator isn't full of water, and consider replacing it, as well as getting an inline style as redundant insurance.

If the problem is with the compressor, there should be some moisture coming out of the brush with no paint involved at all. Looking at a picture of the Standard, it certainly appears that the water seperator should be up to the job of removing the small amount of water created by compressing air. My Senco has a valve on the tank and it's a rare day when I see any moisture when I open it. I also have a Iwata knock-off with no water valve and have never had the problem you describe. Anyway, blow a few minutes of air through an empty brush. If there's no moisture then and there is if there's paint in it, I'd wonder if you don't have a clogged nozzle that would cause spitting and all kinds of uneven spray patterns.

Heavens Euros have to pay to play: you want to keep your national budgets balanced or something?

Eric