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Thread: HVLP Runs?

  1. #1

    Default HVLP Runs?

    Hello everyone, I am a new to using an HVLP gun and it shows. I have sprayed a few times in the past with a Sharp siphon gun for the most part I was happy with the results.... * I am a hobbyist that only paints once in a year or so it is hard to figure out what is going on without spraying regularly. I have painted a few cars over the years with good results but this hvlp gun makes me look like a kid messing around. VERY Disappointed.....
    *I need some advice on gun setup.....
    Today I sprayed with a Central Pneumatic HVLP gun Item 69705 it supposed to be capable of spraying with good results. However, I have used it twice in the last couple years and both times ended up with runs. The pattern looks good I am going at the same speed I would with Siphon gun but it appears to need me to go much faster as I have runs all over the fender.

    Spraying: Nason single stage full cryl acrylic enamel gloss black...
    Settings:
    -40 psi at gun with trigger pulled
    -Air knob: on bottom of gun opened all the way... (Does this sound correct)
    -Fluid knob: this is the one I am concerned with I had it opened 3 full turns from in all the way. It will turn 5.5 full turns total. I am guessing I need to close the fluid knob to around 1.5 turns open to cut down on the volume of paint?

    It sprayed on and looked good but a little heavy/thick. I walked away and came back and all of these runs had started that were not there just after spraying they took a while to form....

    Thanks loosing my mind.....

  2. #2
    Join Date
    Nov 2006
    Posts
    2,148

    Default

    I think you answered your own question.

    it appears to need me to go much faster as I have runs all over the fender.

    I think you just need to play with the gun a little to get the feel of it. Im for opening the fluid knob all the way and air knob all the way. That way you will have the same settings every time you use the gun. If you start playing around trying to adjust the flow of paint it will act differently every time you make an adjustment and that will prevent you from getting a natural feel for the gun. If it sprays heavy then move fast and/or pull the gun further away from the surface. I try to spray from the same distance all the time only adjusting my speed of travel to fit the paint flow. That way I only have one variable to deal with.

    Bob K

  3. #3
    Join Date
    Nov 2005
    Posts
    45,869

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    How many coats did you apply? If you applied more than one be sure to allow that first coat to dry to the touch before applying the second and third.

  4. #4

    Default

    3 coats I was shooting for 4 coats so I had plenty of paint to wet sand and buff out but 3 coats was much thicker than intended as it it ran and covered much quicker than expected. I did wait for flash times between coats....

  5. #5
    Join Date
    Nov 2005
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    45,869

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    Quote Originally Posted by brandonA. View Post
    3 coats I was shooting for 4 coats so I had plenty of paint to wet sand and buff out but 3 coats was much thicker than intended as it it ran and covered much quicker than expected. I did wait for flash times between coats....
    Most low cost HVLP guns tend to not atomize as well and conventional guns so it's critical to allow that first coat to dry to the touch before applying additional coats. Also the larger droplets also tend to go on thicker and run more easily. I'd recommend getting a better gun before your next paint job.

  6. #6
    Join Date
    Nov 2005
    Location
    lower Michigan
    Posts
    31,657

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    You have a really steep hill to climb painting based on the fact that you have what is probably the cheapest paint gun made and you have no/very little experience spraying paint.

    That paint gun you have is a Chinese copy of an atleast 30 year old Sata NR92 (which was a crappy gun to start with). HVLP spray gun technology has come a long way in the last 30 years and I personally am still not particularly impressed with even current HVLP technology. I much prefer LVLP or compliant guns as opposed to HVLP.

    You are not going to find a decent spray gun for less than a $100 and the cost rapidly goes up from there. I have a Warwick LVLP spray gun that I paid $130 for at least 10 years ago. That is my go to spray gun. I have owned top of the line expensive spray guns and most of them I wasn't particularly impressed with.

    I agree with Len, ditch the cheap harbor freignt gun and get a better spray gun. Harbor freight does sell 2 guns that cost over a hundred dollars and they are actually decent spraying guns. Their downfall is NO replacement parts are available. (no gaskets, no fluid tips/air caps, no needles can be bought separately).
    LS says "Lets Go Brandon". He's like that.

  7. #7
    Join Date
    Nov 2005
    Posts
    45,869

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    I agree Phil the least expensive gun I normally recommend is the DeVilbiss Finishline which comes with several fluid tips and parts are available but the gun costs around $180. I haven't used this new model but DeVilbiss has always been a reliable company to deal with.


  8. #8
    Join Date
    Jan 2019
    Location
    Ontario Canada
    Posts
    91

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    "-40 psi at gun with trigger pulled"
    Any of my HVLP guns are MAX 26 psi inlet pressure.

  9. #9
    Join Date
    Nov 2005
    Posts
    45,869

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    Quote Originally Posted by JMTC View Post
    "-40 psi at gun with trigger pulled"
    Any of my HVLP guns are MAX 26 psi inlet pressure.
    Different guns can be engineered differently and the inlet pressure can vary so read the manufacturer's recommendation for the gun you're using.

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