Spray problems

[rdzat]

This week i finally used my hlvp gun for the first time, i sprayed dupont sealer over the primer, what a mess i would'nt say i have orange peel its more like warts (just kidding but its bad) i have been sanding with 500 ever since. what did i do wrong? i mixed the products as instructed temp was 70 degrees i have a 5 h/p compressor with a 25 gal. tank i adjusted the regulator at the gun to aprox. 15 psi, i'm using a 3/8 air supply line, i guess what i'm asking how do i adjust the gun i'm thinking too much paint was comming out of the gun it did not seem to atomize enough, i hope somebody can give me some pointers because my arms are getting tired of sanding this stuff and i dont think they can take another round of sanding that stuff is hard to sand not like primer. Ron............

 

[Jim]

I don't use an hvlp but,I would guess the 15lbs is what caused your problem,I use 50lbs with a conventional gun.I'm guessing the book you got with the gun said 15lbs at the tip,unless you have a gauge,you can't measure tip pressure,I'm sure one of the hvlp users will tell you what hose pressure they run thiers at.Don't worry,you'll have a good answer soon!

 

[rdzat]

Yes my book that came with the sprayer said about 15 psi to the gun i did bump it up to about 20 psi maybe i'm interpeting this wrong the compressor gauge is set for 100 psi, i am new at this as you can tell, i have sprayed with a conventional gun but that was only on tractors w/ industrial paint never had any serious problems. I have to get this right before i start spraying the high dollar dupont b/c c/c. Ron......

 

[Jim]

I'd be willing to bet the book said 15lbs "at the gun" not "to the gun"Meaning at the tip and like I said,you need a special gauge to check that.I would bump up your regulator to 40lbs like stretch said.Leave the one by the compressor at 100 and turn up the one by your gun to 40)Try it on a test panel and see if that takes care of it.

 

[Stretch]

I've been worrying about my compressor (Craftsman 6hp/33gal) keeping up with amy DeVilbiss HVLP. I shot a motorcycle helmet using PPG. I had the regulator set to about 40psi thinking I'd get about 5lb drop in pressure through the line leaving me with about 35psi at the gun. The manual says that 35psi at the handle will deliver the necessary 10psi at the tip. With those settings I got a nice clean finish (after some adjustments). I know the compressor doesn't have the recommended CFM but it seemed to work for me on the small helmet. Hope that helps.

-Stretch

 

[rdzat]

Thanks for the info. i am almost sure now that was the problem. Ron................

 

[TWISTED]

HVLP guns use lower pressure than conventional guns. That is how they eliminate a lot of the overspray. Your problem may be that the paint wasn't strained. There may be some solids floating in the sealer that you diddn't see which would cause some lumps of crap in your finish. You can find strainers where you buy your paint or in a pinch use your old lady's nylons. She ight not like it but they get the job done.

 

[DenB.]

What do you all think of a Devilbis GTI gun? I was talking to a guy who works for a friend spraying and he told me ( bang for the buck) it's maybe one of the better guns to get.

 

[Stretch]

Mine worked great but I'm a newbie so can't compare it to others.

-Stretcj

 

[shaunboy]

Hi rdzat

HVLP is used by around 75% of us painters here in New Zealand.
Ive been using it for about the last 4-5 years.
I own a "devilbiss GTI mellenium"
Has your compressor got an adjustable gauged regulator on it??? Not just a guage that shows the holding tanks' pressure.
If not you should get one for HVLP spraying.
Me and the guys at work set the regulator to between 40-50 psi. 50 being maximum.
And does your gun have a built in air adjustment?
If not you can get one that will screw into the gun and the hose fitting screw in that.
HVLP is alot more diffuct to spray with than conventional higher pressure guns for a beginner..You need to hold the gun almost twice as close to the panel and spray nearly twice as fast .
At the same time the gun strokes and spray direction need to be a little more even and direct.
When i first changed to HVLP i was shocked.

but soon got used to it and now find it awsome.
Hey? what size is your gun fluid tip?
As a beginner id use a 1.4 "as 1.6 or more will be the cause of too much paint coming out even if you do wind in the fluid control on the gun"
What sort of gun do you have?
Im a big GTI fan but i heard good stories of 'Sharpe and 'Sata
Any leading brand should be good I guess or they wouldnt of produced them in the first place.
If its at all possible find a professional painter and ask him if you can watch him while he sprays with a HVLP gun so you can see the difference with your eyes between HVLP and Conventional spraying.

GOOD LUCK.

 

[rdzat]

Thanks Shaunboy for the tips i have a Sata w/ a 1.4 tip and i do have a adjustable reg. at compressor and one at the gun i will take your advice and visit a painter to get some tips. Thanks Ron in So. Calif.............

 

[trigga]

15 lbs is not even close. turn the regulator on the gun up to about 45psi and try it again.

Most HVLP guns need that much to get the 10psi at the air cap that it needs to work right...

 

[rdzat]

Yep thats what it was i turned the regulator on the gun to 45 psi and it sprays perfect, thanks guys,its laying down paint as smooth as babies bottom Thanks. Ron........