Spanjaard
curious about this one

Treehugger
Hm, I just had a look at this video from IWATA on youtube (no sound), and their "deep clean" doesn't seem that mysterious. I know I don't really screw off the 'needle cap' and the 'nozzle cap'.

There is a tiny hole at the front inside, no idea if that is dirty inside on my airbrush, presumably where the air comes out from the compressor. I poked around with a fine tip q-tip, but no dirt.

Youtube Video

Treehugger
Another thing, I noticed that I saw tiny bubbles in my paint cup, even when I wasn't pressing down on the air trigger. Any idea what that might indicate? It is as if, something maybe was clogged at the nozzle perhaps, the same way some people cover the tip of the airbrush to mix the paint cup by reverse flow. I never do that, never with my finger tip, probably not healthy pressing air into the skin, should anything get inside.

Treehugger
I took out the 'needle packing head' (screwing it out) from the inside, and for the first time, I cleaned the needle canal that leads from the paint cup, to the silicone needle packing ring that tightens around the needle inside the airbrush. I saw some gunk in the canal, and also some gunk on the back end of the needle packing head.

I am not happy with my paint flow, and I can't quite tell if it is because I airbrush at 20 psi, or if there was something dirty inside the airbrush blocking the paint flow.

Btw, the paintcup lid, has a hole that has to be open to avoid a vaccum, that one I know was clean from the start.

I bought a new big O-ring that goes around the nozzle (still in the package unopened), I thought the old one looked ok still. Unsure if that might be an issue, or, I wouldn't know what issue might come from having a leaking gasket around the nozzle part of the airbrush.

Spanjaard
well, i do not have an Iwata, but my experience says that bubbles in the cap means something is stopping the correct flow. in other words, the airbrush is probably dirty. if i see that, I stop and clean it again.
of course, some damage in some parts may cause the flow to be interrupted and send bubbles to the cup. but never had it even when the nozzle was really damaged.
I usually cover the exit to sent air back to mix paints and/or clean the airbrush (loaded with thinner). i doubt it will send anything under your skin. air will scape between your fingers rather than entering under your skin, in my opinion. In my case, i never use the airbrush without gloves. i have my gloves on most of the time when i am with working on a model.