Recently I have had issues with airbrush paint pulsing, even though my air pressure/flow remains constant. By pulsing I don't mean spitting, just the paint flow cycles on and off.

It happens with both my gravity dual action, and siphon single action brushes. Also occurs regardless of how thin the paint is, and will even pulse with plain water or pure alcohol.

It's not a dirty airbrush tip, as the before today I hadn't used the single action brush, and I only sprayed pure alcohol through it, no paint. I have also swapped the tip and needle of the double action brush for an unused spare with no change.

Compressor has a 21 litre tank and adjustable pressure regulator. Have tried everything from about 10psi all the way up to 60 with no discernible change. Airflow has no pulsing that I can see but paint pulsing is very obvious, and lasts a good few seconds at a time while air continues to come out of the airbrush.

Last time I did any spraying was over 6 months ago and this problem didn't exist. Frankly I am at a loss how to fix it so any suggestions would be welcome.

Iain,
I'd recommend trying to isolate the problem buy eliminating possibilities. Since the same effect is happening with two airbrushes, I'd recommend you try a different air source to see if the problem still occursu. A friend's air source or a cheap alternate like an airbrush hose adapter for a car tire or something like that.

Also, what airbrushes are you using?

Paul H

Common factors... air source and paint. Rule them out first. I suggest you try spraying water. If that still has issues then I would say try a new air source. The other issue may be water in the lines guming things up. Good luck

The airbrushes are are pair of cheap ones. The single action is a no name I got for about $20, and the double action appears to be an iwata style clone that I got from the local auto parts store.
I do have an actual brand new iwata but I don't want to pull that out of its box till I have this issue sorted.
Unfortunately tyre adaptors are few and far between in these parts. Same with airbrush propellant cans for which I do have an adaptor at least for the single action.

Have you checked for leaks at the hose connections? Are the connector threads sealed with Teflon Plumbers Tape? — can be found for a few bucks at your local hardware store. HTH.

—mike

Are you using a moisture trap?
Sounds like water in the hose that temporarily blocks the line until enough pressure builds to blow past the blockage thus the pulsing. Try draining your hose and blow it out and check your trap to see if it's working correctly.

Maybe a faulty check valve?

sounds like a bad regulator on the compressor . or moisture trap ? .

The fact that it occurs with both of your airbrushes seems to indicate it's a compressor problem- you mention you have a tank compressor-- have you drained the tank recently? An air tank full of water has the effect of rendering your tank compressor to a "tankless" compressor. Since the tank becomes useless, the air will pulsate as the piston moves the diaphragm up and down-- just as if it didn't have a tank at all. Usually if you have a water trap, the trap will fill faster than normal. If you don't have a trap you should notice more water in the airbrush. Most tank compressors have a nut or hex-head nut on the bottom of the tank for draining, it's there for a reason but 50% of us seldom think about draining the tank -- don't ask how I know this! If you live in an area with wide temperature variations, or high humidity, your tank will need to be drained more often-- I live in humid area, and even if I don't use my compressor for a few months, I still find water inside. VR Russ

Tank is bone dry, not a skerrick of moisture to be seen.
Haven't had a chance to test anything, too much real life going on.
I did remember I have an old tankless diaphragm compressor I haven't used in years, but need to attach an adaptor before I can hook up any of my hoses.

In the end I ditched the bodged dual outlet and replaced all the fittings with some slightly higher quality ones, and that seems to have solved the issue.
Hard to tell for certain as I have only sprayed a clear coat, but it certainly seemed to be coming out more evenly.

Hopefully on my next model I won't have so many problems.