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My airbrush is...spitting?

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  • Member since
    March 2021
My airbrush is...spitting?
Posted by bapowellphys on Thursday, November 11, 2021 10:43 AM

Hi all,

I've been experiencing an annoying phenomenon lately with my Paasche H-series (siphon-fed) airbrush, in which, while airbrushing under normal operation, it will randomly shoot out a burst of liquid. I've had this happen with thinned Tamiya acrylics and just now with Stynelrez primer straight from the bottle.  It seems to happen only after fairly continuous airbrushing for several (5-10) minutes, as occurs when painting or priming a decent-sized area.  Once it starts, it will continue to randomly spit like this every 5-10 seconds.  

The last time it ocurred, I stopped brushing, disassembled my brush, and gave the needle and tip a good rinse to make sure there were no obstructions.  This didn't help.  I then emptied the paint cup and flushed it as well, yet the problem persisted.  It does not seem to depend on pressure: I've seen it happen as high as 30 psi and as low as 20 psi.  

Has anyone had this problem?  Any ideas or help would be much appreciated.

Thanks

Brian

Check out my latest builds here!

  • Member since
    July 2004
  • From: Sonora Desert
Posted by stikpusher on Thursday, November 11, 2021 11:37 AM

Are you in a medium to high humidity locale? I used to get that sort of thing when I lived near the ocean. Now in the Sonora desert, only during the monsoon. Do you have a moisture trap on your compressor? Or does your compressor have a tank, and if so, do you open the drain valve to allow accumulated moisture to drain out after a session?

 

F is for FIRE, That burns down the whole town!

U is for URANIUM... BOMBS!

N is for NO SURVIVORS...

       - Plankton

LSM

 

  • Member since
    April 2020
Posted by Eaglecash867 on Thursday, November 11, 2021 11:51 AM

Yup, sounds like moisture condensing in your air source.  After 5-10 minutes of airbrushing, the air will be much warmer and able to hold more water vapor.  

"You can have my illegal fireworks when you pry them from my cold, dead fingers...which are...over there somewhere."

  • Member since
    March 2021
Posted by bapowellphys on Thursday, November 11, 2021 12:53 PM

Thank you both.  I do have a bit of water in the regulator.  What's the best way to keep this from happening in the future?  If I press the valve on the bottom of the regulator, the water flows out.  Should I just periodically empty the water?  Or will this still be a problem once the air gets sufficiently warm to pick up moisture?  Thanks again!!

Check out my latest builds here!

  • Member since
    July 2004
  • From: Sonora Desert
Posted by stikpusher on Thursday, November 11, 2021 12:58 PM

Does your regulator have a moistur trap?

if not, you'll need to get one. If it already has one, thats beyond my experience. 

 

F is for FIRE, That burns down the whole town!

U is for URANIUM... BOMBS!

N is for NO SURVIVORS...

       - Plankton

LSM

 

  • Member since
    March 2021
Posted by bapowellphys on Thursday, November 11, 2021 1:36 PM

Yes, it does.  The moisture trap is what I was calling the regulator earlier.  So the moisture trap is meant to prevent this kind of thing from happening?  

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  • Member since
    August 2021
Posted by goldhammer88 on Thursday, November 11, 2021 2:00 PM

Yes.  I use one of the small in line "pumpkin" traps.  I get them from harbor freight at around a buck each.  Can also get from most part house's.  They are 1/4 NPT.  I have mine set up with a regulator, the pumpkin and then the AB hose.  The regulator is set up on a quick disconnect, and on a Fortress 2 gallon tank compressor.

The water trap you pictured isn't that effective, even in a shop setting. More than once I'd get as much water out of my grinders and impacts as air. And that was draining every morning, and we had two of them, along with an oil trap.  We used the pumpkins right before paint guns.

  • Member since
    January 2005
  • From: Cave City, KY
Posted by Watchmann on Thursday, November 11, 2021 8:22 PM

bapowellphys

So the moisture trap is meant to prevent this kind of thing from happening?  

Yes, it is.  I've had the same issues as you.
 
Here are some other suggestions...
 
Keep your compressor on the floor and direct a fan onto the compressor's head to keep it as cool as possible. 
 
Buy a second air hose like this one.  A longer air hose will allow the air to cool before it gets to your brush. Attach one end to the compressor and the other end to the air inlet of your regulator\moisture trap.  Mount the regulator to your workbench.  Attach your airbrush hose to the air outlet of your regulator.
 
Keep an eye on the moisture trap, and open the valve whenever you see water condencing inside. 
 
You might also consider getting a compressor with an air tank.  Remember to drain the tank after each painting session if you do get one, or it will rust from the inside out.
 
Good luck!
  • Member since
    March 2021
Posted by bapowellphys on Friday, November 12, 2021 8:42 AM

Thanks everyone for the help and suggestions!  I'm going to try out first a second moisture trap that connects directly the airbrush and see if that helps.  I'll also try moving the compressor to the cold cellar floor and use a fan.  Wish me luck!  

Check out my latest builds here!

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