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Hi guys,

I have a Sotar 20/20 that I've had for 5 or 6 years now. It's suddenly started acting funky, and I think something broke internally, but I thought I'd ask to try any suggested simple fixes before contacting Badger for an RMA.

I've been seeing a lot of bubbles in the cup, but not little, slow bubbles, like a clog? Air bubbles in the cup are pretty much the most common airbrush problem that exists, and it's usually a clog in the nozzle but this is more like... shooting air. I broke it down, cleaned it carefully, and then just put some water in the cup. With water, it literally blasts it out of the cup.

I'm using the head that exposes the needle, so I can clearly see the needle passing through the nozzle. I'm 100% sure the nozzle is clear, if I take the nozzle out and slide the needle in and out, it passes though easily and it's exposed as much as it typically is when working. I own 4 airbrushes and am pretty familiar with diagnosing a nozzle clog at this point, this is very different - I've never seen it do this before.

Would a broken or worn needle seal, inside the body, cause this? The needle seems a little loose. It comes with an allen wrench to adjust it, but that doesn't seem to be working - no matter which way I turn the wrench, it's not tightening (or does it appear to stop).

The PTFE o-ring that goes around the head is present and in good condition. Everything is tight and well sealed. I swapped to a different airbrush using the same compressor/line/regulator, so the air supply is solid.

Any last minute ideas?

Thanks!

Is the annulus between the air cap and the nozzle clear? So not the nozzle itself but the gap around the nozzle? And does air blow nicely through it when there's no paint in the cup?

Is the nozzle seating in the right place?

After that, is the nozzle sealing properly against the body of the brush?

The Sotar seems to have a different seating mechanism than I'm familiar with, usually there's a seal between the nozzle and the body of the brush which keeps paint in the nozzle and air out of the paint cup, but I'm not sure how that mechanism works on the Sotar. Typically if there's some build up, seal damage or a small scratch on the mating surfaces they won't seal properly and air can get from the air cap back though to the paint cup instead of all going out the aforementioned annulus around the nozzle.

Needle seal shouldn't be a problem unless the Sotar has some whacky air passages (unless you're talking about a different seal to the one I'm thinking about, the needle seal seals off the paint from getting to the back of the brush, there's no air pressure on it).

Here's a generic picture of how an airbrush works, the "nozzle" is the "material tip", so you can see the only way for air to get in to the paint cup is either down through the front of the nozzle (like when you backflow the brush to clean it out by clogging the front of it with a tissue) OR through the base of the nozzle (in this case through the threads, but some airbrushes don't use threads so seat the nozzle).

http://paulbudzik.com/tools-techniques/Airbrushing/airbrushing_for_modelers.html

If you're sure the airbrush nozzle is clean, then the problem may be between the cup and the air valve. Dried paint in this location can cause the needle to not seat properly in the nozzle, causing funky problems. It's worth a check before sending it back to Badger.

Thanks for the tips, and that diagram which shows me where to look (and why it's not the needle seal). I've ordered a replacement PFTE seal and will go poking around in the annulus (snicker).

The other one I should have mentioned is if the paint passage that leads to the nozzle is part of a removable head, that could also be a source for air to get in to the cup. Didn't think of it because neither of my airbrushes work that way, both of them the paint passage is integral to the body of the brush rather than the removable head.

I figured out what it was. I'd like to say that it was some super complex issue, but the truth is it was just a thoughtless little dumb mistake: I'd installed the nozzle wrong. Normally the nozzle sits directly atop the head, prior to the 2 seperate aircap pieces, but it's possible to install the first half of the aircap, then the nozzle, and then the final aircap piece and have it mechanically all fit and appear to function. I've probably taken apart and reassembled this airbrush a hundred times and I'm not sure how I managed to do it wrong this time. Well, the good news is it's working great again.