Problem with siphon feed touch up gun

Discussion in 'Finely Finished' started by sleazy pot pie, May 25, 2020.

  1. sleazy pot pie

    sleazy pot pie Tele-Afflicted Silver Supporter

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    12BCD782-9EE4-4369-87AC-4726EDADEA38.jpeg Why am I getting air bubbles in my finish? Not small random ones, but pervasive and large bubbles. No matter what pressure, viscosity or medium. 9ABC0042-D884-4F15-AFB4-92D023CFB78A.jpeg 77F7CBFF-8C30-449C-A28A-EB1D269C6B98.jpeg

    this is zinnsers 123 primmer thinned a little with some blue added
    I have tried super low and high pressure
    I have tried really thinning and not thinning at all.
    Let me preface this by saying, for a home hobbyist, that I have sprayed a ton of lacquer over the last couple of years. I feel like I have a decent grasp of it and how to trouble shoot issues.

    that being said, this one gun style is giving me fits. I have purchased 3 different ones(amazon exchanging actually) and still get the same problems.

    Does this have to do with the canister not being sealed? Is it from the siphon skipping and allowing air in? Kind of the reverse of a kid blowing bubbles into their milk?

    Could use a little help
     
  2. RodeoTex

    RodeoTex Doctor of Teleocity

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    Wow, I have a very similar gun and never experienced anything like that.
     
  3. sleazy pot pie

    sleazy pot pie Tele-Afflicted Silver Supporter

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    Couple of things I thought of.
    I had this body on the ground, elevated on a box.
    I was standing over it and shooting down at an angle

    should I have it hanging and keep the gun parallel to the ground?
     
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  4. sleazy pot pie

    sleazy pot pie Tele-Afflicted Silver Supporter

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    Roughly what psi are you using at the trigger?
    I am at about 25 psi with it pulled
     
  5. sleazy pot pie

    sleazy pot pie Tele-Afflicted Silver Supporter

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    DBBD451B-7C3C-4C5B-A9B8-ACF7A371F70A.jpeg
    I added some Teflon tape where you see the blue arrow just now when I cleaned out the primer.

    I wonder if the red circle could be the issue?

    I just feel like there is something that isn’t completely sealed
     
  6. Speedy454

    Speedy454 Tele-Holic

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    That looks just like the touch up gun I threw away a few years back...

    Several things come to mind, but I am no expert.

    The fluid needle is backed out way too far, applying way too much fluid.
    Possibly incompatible products. Tint, paint and solvent may not be 100% compatible.
    Applied way too wet.

    The touch up gun I had that looked like that was from Harbor Freight. It was very temperamental. Sometimes I could shoot clear so smooth that I didn't need to wet sand before buffing. Sometimes it sprayed a mess. Mine had a Teflon lined cup. The final straw was that I was getting these tiny flecks of white in my clear. It ended up being flakes and flecks of Teflon out of the cup. If I remember right, it was positionally sensitive. I don't think it liked shooting down. I switched to a cheap HVLP set of guns and that solved many of my problems.

    Put a water separator and a pressure gauge at the gun. That way you don't have to guess the pressure drop on your lines
    You need about 25psi at the gun with the trigger half pressed allowing air flow through the gun.

    But all that crap hanging off the back of that already top heavy gun is a PITA. Make a stand for it so it doesnt fall over.
     
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  7. Peegoo

    Peegoo Friend of Leo's

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    It is probably a small air leak at the top of the siphon tube in the paint container.


    Also, make sure your air is as moisture-free as possible. High humidity levels can cause this too.
     
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  8. dkmw

    dkmw Friend of Leo's

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    Temperamental guns are as old as the hills. So you can rest easy knowing you’re not the first.

    Normally I’d advise complete disassembly/clean/reassemble, but if this is third one with same problem...

    This reminds me why I’d rather just use prevals for something small like a guitar.
     
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  9. sleazy pot pie

    sleazy pot pie Tele-Afflicted Silver Supporter

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    Thanks guys
    I do have a regulator and moisture trap on the end of line just before the gun.
    20-25psi with the trigger pulled half way(before anything comes out) is where I keep it
    The fluid needle was backed out that far because I had just cleaned the gun.

    Hopefully the Teflon tape where the gun meets the cup will help

    I think you have a good point about not shooting down.
    It is about to start pouring down rain, so I am done for the day, but will let you know what happens next time.
    Thanks again
     
  10. tewiq

    tewiq Tele-Meister

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    I have the same gun, 0 problems ,except the balance is crap, lay the hose over your shoulder and it works. if it sprays a constant flow then it's probably a contaminant on the body or incompatibility between your products that your mixing to spray.
     
  11. eallen

    eallen Friend of Leo's Silver Supporter

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    Yes on hanging and keep the gun parallel. For one, you never get an even coat shooting down because gun tilt is hardly ever fully perpendicular to the surface meaning uneven fan.

    Eric
     
  12. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

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    What's it sealed with?

    Temperature?

    Humidity?

    What needle/air cap combo? Have you called the manufacturer or talked to the seller? The support desk is your best friend.

    Are you measuring the wet mil thickness? It looks VERY thick to me.

    25PSI with a conventional gun? Sorry, but I've never seen anything atomize well at pressure that low.

    Honestly, this is a good example or why I only spray by HVLP(little jobs by aerosol at times) - at 4-10PSI the control of an HVLP is great, atomization flawless and it's easy to keep the wet mils down to 1-2 per coat.

    You can get a good non-bleeder HVLP for $250-350 new, and a cheap bleeder for $120 that will work great IF you're real careful.
     
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