Need a painter's advice

Using an HVLP gun with the cup on top...for small stuff, but it needs to be able to lay a smooth surface when I spray clearcoat. Right now, it's looking like I'm spraying over something covered with sand.

First off, what is the vertical knob on the bottom of the handle, by the air inlet for?
Second, what does the knob straight back from the nozzle do?

While I'm sure one of these lets more paint come out (or not), they don't seem to DO anything on mine. I DID find the spray pattern knob...

Question: if you gun was spraying out a rough layer, what would you do to smooth it out?

Thanks!

 

The knob on the bottom of most guns is air pressure adjust.

Is this a Harbor Freight purple gun? They are not HVLP and need 35-40psi, just because it is gravity feed does not make it HVLP.

There should be an adjustment for spray pattern on the side that shows a line going from thin to thick in a curve around the knob. Also the needle adjustment on the back.

As for smoothing it out, what kind of paint?

 

What gun do you have and what type off paint are you using?

 

Also is the gun new or has it been used?

 

The knob straight back from the nozzle is the fluid tip adjustment. The farther that you let it out the more material is released from the gun.

To me it sound like you do not have enough material exiting the fluid tip at the end of the gun regarless of the model, make or style. Turn this knob all the way in an turn it back 2 1/2 tuns. next adjust your spray pattern so that it makes a nice oval shape. Check this by putting a piece of masking paper on the wall and give it a 1 second shot.

if your pressure is too low it may be a factor as well. The last knob opens or closes the pressure valve.

Lastly IF THIS DOESNT HELP, you may not have enough reducer or too fast of a reducer. Between 15 and 25 degrees celcius you want a medium reducer any hotter you want a slow reducer.

 

My bet is more on the mix of the paint rather than the gun set up. to thick needs to be thinned out a little. another thing that will make it look like sand is dirt on the surface.

 

Alright, I cleaned this sucker from stem to stern and then set it up like hotflint suggested and it's working like it should...nice smooth coating and all is well...

Thanks to all who responded...

 

Glad I could help!!!

 

Well crabs, guys, I’m back again…I thought I had this deal figured out, but not so fast.
<O</O

I’m using a brand NEW HVLP gun at 20psi, shooting Dupont Clear (496-00) with the activator (483-78) and here’s the deal…there are tiny voids in the finish…and I saw them get spit out of the gun.
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I’m using brown paper taped on my trash barrel and doing a test, I saw it spit out 2- somethings-…but the gun is clean.<O></O>
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On a flat panel I just sprayed, there were some spots that looked as if I had sprayed over a dot where oil had been; the paint just would not flow onto those spots.<O></O>
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It almost HAS to be in the mix, but it’s my understanding that clear (496-00) is to be used straight out of its can (NOT reduced) and the activator added to it in a 4:1 ratio. Isn't that right?
<O</O

I’m out of ideas, but it isn’t doing me any good to go back and start over if it still won’t spray right.
<O</O

H-E-L-P???

 

Sounds like you're getting oil in your air line.....
Also, do you have a gauge at your gun? And is that set at 20psi? If so, bump it up to 40...

 

"Sounds like you're getting oil in your air line....."

or water. the voids are fisheyes, and they are from a contaminant. Also, did you strain your paint?

 

for small stuff id get a little gun with a 1.0 tip on it ..

 

+1... you're getting fisheyes. Either it's something that you put on the panel from your body, or it's in your air line. Any good oil/water filter will knock out 99% of that. Let your clear dry for 24 hours. Scuff it with 800 grit, then go over that with a dry maroon scotchbrite pad, paying particular attention to the fisheyes with the scotchbrite. Then use some Dupont Final Klean 3901S and a clean paper towel to wipe the entire panel down. Then, with latex gloves on, wipe the entire panel down with a good tack wrag, THEN re-shoot your clear with 2% - 5% mixture of fisheye eliminator (Dupont 359S-P) (about a capful in a quart gun).

That should stop the fisheyes from getting any deeper, but you'll need to 'bury' the ones that are currently there, let it dry up (shrink as far as it's going to) hard, then either try to polish, or put on one more gloss coat of clear to finish it out....

 

Gauge at the gun is set at 20psi as per the manuf.
I thought low pressure meant LOW...40 seems like normal...

Strained paint and the gun has a built-in strainer.

Don't have a lube line in the system...now, water? I will check.

 

Either the oil is coming from the line... or its already on your surface. You need to clean and scrub with a waz and grease remover. A fisheye is not due to gun setup, its due to a contaminated surface.

 

Most HVLP's want 10 psi max at the tip, which generally takes much more than 20 psi at the gun inlet, The LP of an HVLP is low pressure.....on the OUTPUT, internally they drop the pressure low.
Also, adjust your air pressure with your fan adjusted where ya want with the trigger pulled. As that will have an effect on the gauge reading. I open the air inlet knob on the gun all the way and use a separate reg on my guns....
I've never gone by "manufacturers reccommended settings"...haha. Most painter's have their own little setups and personal adjustments, to suit their style....just play with it a little at a time to find settings you like and stick to 'em.

Lose the "built in" strainer in the cup.....

 

If it is oil contamination, it is probably coming from the compressor pump. They all lose a little around the rings. I try to use a dedicated hose that has not had oiled air tools on it. I fear that a little leaks back from the tool to the hose when connected and sitting. Maybe paranoid...but I rarely have a problem. I also filter my air just outside the compressor and then do it again where the flex line attaches to the hard pipe across my shop.

 

you definately need a good dessicant type dryer/filter it sounds like contamination to me too the best type system would be a refrigerated dryer and a 3 stage dessicant type filter at the gun air supply , thats what we use

 

i set my paint room up with its own comp lines and filters nothing get hooked to that air line but a paint gun ..

before i did this i used 1 comp for every thing till it slipped oil by the rings wait till that happens it messed up a lot of stuff a few projects my gun no matter how much i tried to clean that gun it was a fish eye machine ..

dont run synthetic oil in you comp as well. i dont care what kind of traps you have they will not remove oil from the air..

 

Thanks for all the replies- got some good filters now...

But LOOK- is this correct??:

"it’s my understanding that clear (496-00) is to be used straight out of its can (NOT reduced) and the activator added to it in a 4:1 ratio.
Is that right?"

Ready to try again, but want to make sure that NO reducing is correct...

THANKS!

 

isnt that nason select clear?

the higher majority of clears out there do not use a reducer. the most common mix ratio is 4 to 1.

but........

that has nothing to do with the clear your using, uless the tech sheets says to mix it to that ratio. DO what the tech sheet says to the T.


if ur on a budget, or dong want to invest in expensive air filtration setups.... u can do what i do. the shop im painting out of has the worst compressor. im not bringing my compressor that i own in. i use a 20 dollar regulator/filter/oiler from harbor freight. for get the oiling part. i leave that alone. i use a 50 foot airline. then the trap, then another airline. at the end of the gun, i use the 8 dollar mini dessicant filters from harbor freight. its very cheap and ghetto, but im not painting in a booth, in a shop that gets fab work and fiberglass custom audio work done.