Author Topic: airless gun spiting/HVLP gun cleaning  (Read 4843 times)


  • Guest
airless gun spiting/HVLP gun cleaning
« on: March 10, 2006, 11:39:02 PM »
Hey guys,
I have a graco STX airless sprayer.  I was wondering why at the end of nearly every pull on the trigger the gun spits.  I'm not getting a clean cutoff of paint when I let go of the trigger.  I use the graco contractor 2 gun with the tip that it came with from the factory.  I only spray latex out of it and it has a latex tip.  What do I do to stop the spitting.  I've used flotrol.  I wan't to spray at the lowest possible pressure right?  I know that if I'm spraying with to high of a pressure I get way to much paint on the wall, not to mention the sags.  The problem with the the low pressure is I'm getting tails and lines in my spray pattern.  I'm thinking about upgrading to a ultra 390 or 395 but I just bought the STX which the guy at the paint store said is better than the 390 cause of the electronic pressure control.  Anybody have any ideas?  Also, what size tip should I be using to spray interior latex?  One more question, is it ok to to clean my HVLP gun by shooting laquer thinner through it instead of taking it apart every time?  
Look foward to hearing from you all
Sorry so long winded :)    ;D ;D ;D


  • Guest
Re:airless gun spiting/HVLP gun cleaning
« Reply #1 on: March 11, 2006, 08:07:15 AM »
Two good signs of your pressure being too low is 1) tip "fingering" and 2) leaky gun/spitting.

Sometimes a new tip needs to be broken in a bit, especially the smaller ones; 4-13 and smaller. Are you using the RAC5 tips or the newer RACX guard and tips? I find that Graco's improvements in the RAC X upgrade actually ARE an improvement..

Another problem (for me at least) is that gun you're using. The older Contractor series has a needle set up that can be over-tightened, which can (and has) bent the needle assembly. That causes incorrect seating and that causes leaking and spitting...So far the new Contractor guns have been real good to me, though there are cheaper guns that don't last as long between re-kits but seem to perform ok...

Start with what you have...Make sure your needle is set correctly (factory setup is not always optimal) and experiment with your pressure setting...

Good luck


  • Guest
Re:airless gun spiting/HVLP gun cleaning
« Reply #2 on: March 11, 2006, 08:11:27 AM »
Aw jeece, I guess I could answer your other questions... ::)

My favorite Graco tips are the 517 for walls and ceilings and the 413 for trim and doors, if I'm using latex...With alkyds the tip size goes way down, to a 311 or even a 211...

And yes, you can clean an HVLP with lacquer thinner, are you shooting lacquer? Good old mineral spirits should work fine (assuming you're spraying oil)...I wouldn't recommend spraying latex with an HVLP...

Offline CarlThePainter

  • postingpro
  • Sr. Member
  • *
  • Posts: 371
Re:airless gun spiting/HVLP gun cleaning
« Reply #3 on: March 11, 2006, 09:58:41 AM »
I think upgrading to the best gun Graco makes will solve a lot of your spitting least it did for me.  Personally, I like the high pressure....I don't want to spray at low pressure.  I want to move fast and if I'm getting sags, I'm going to learn how to move my hand faster before I turn down the pressure.  Higher pressure generally results in better atomization of the product.  


  • Guest
Re:airless gun spiting/HVLP gun cleaning
« Reply #4 on: March 17, 2006, 09:04:08 PM »
You have to find a happy medium between your pressure setting and your stroke speed to eliminate the sag fromn higher pressure.  Lower pressure will give u tails regardless of stroke speed.  I own a SW395, same as the 390, and I love it.  The pressure adj is important to eliminate the tails.  I spray about 8-12 gals of latex semi through my hvlp weekly and have no problems.  On the few ocasions ive sprayed oil, it takes me longer to dial in.  And im sure the opposite would be true for someone who predominately sprays oil going to latex.  There is a learning curve with these.  As far as cleaning withlacquer, what are u spraying, if latex, may get gummy,if oil use thinner.  Most definitely use a different hose for each product if u spray oil and latex