Hvlp Atomization Issues!

A

Alec Knecht

Hello all, this is my first post on spi. I am a young hobbyist painter but I have a few paint jobs under my belt. I recently bought the devilbiss starting line 2 gun kit (identical guns with 1.8 and 1.3 tips) and I've been having a lot of trouble with orange peel. Devilbiss says these guns require 13cfm@ 30psi, and my compressor is rated 13.4cfm@ 40psi. The paint doesn't seem to be atomizing enough and yes I've tried fine tuning ALL of the gun settings, as well as air plumbing, paint reduction, etc. My compressor is plumbed with 1/2" pipe up to a 25f 3/8" hose with high flow fittings, so I don't think I have an air delivery problem (that was my initial suspicion). I have tried pressures anywhere from 20-50psi at the gun. I get marginally better results when I crank the pressure up but that also causes a hellacious fog of overspray which I don't THINK is necessary. I am looking for any guidance a more experienced painter could offer. Could I be too close to the air volume threshold for this gun with my compressor? maybe a defect in the gun itself? With my inexperience, I might be making a stupid mistake with my gun setup but I have never had this much trouble setting up a spray gun before. I know I will get more expensive guns recommended to me, which I would love to have someday, but being a college student I would rather not throwdown $500 on a gun right now. I'm just trying to finish this jeep I'm painting with Matrix SS. Any tips or advice is much appreciated, and sorry for the long winded post!
 
A more complete description of your air system might be in order; the make and model of your compressor are not included in your post. A spec quoting CFM at 40psi probably represents an inadaquate compressor. Even so, you should be able to achieve adequate results on small parts and single panels. Also, check out the tutorial on gun adjustment on the SPI main site:

http://www.southernpolyurethanes.com/adjusting-your-gun
 
My compressor is a porter cable PXCM601. 3.7hp, 60gal. It's not the biggest compressor out there but I've heard of people doing overalls with smaller units. Ive been looking into some of the low air consumption hvlp guns but I am skeptical. Either way I'd like to see some success with my devilbiss guns first, as I know people who have the same ones and love them. Checked out the gun adjustment page, I'll definitely give that another try using the technique described.
 
Hmmm, the starting line guns are bottom of the line Devilbiss. I have a finishline 4 gun - a much better gun - which I use for epoxy primer, it is an OK primer gun but an air hog. Couple marginal air supply with a marginal air hog gun and you will probably struggle to get good atomization.
 
That was what I was afraid of. I guess I'll be in the market for a lower air consumption gun until I can acquire a larger compressor. Can anyone tell me anything about lvlp spray guns? Are they similar to hvlp but with a more efficient air cap? I've read that they have great transfer efficiency and some only require around 5cfm, but that's about all I know
 
My son bought me the Eastwood Concours spray gun with 1.2,1.4 & 1.8 tips. It is advertised to use less CFM. I have a 5hp 60 gallon compressor that pretty well keeps up with it. I generally paint only one or two panels at a time. The most I have painted at one time was the body shell of the '55 Studebaker sedan. I was almost overcome by the fumes however so I would not want to try to paint anything else that long in the garage. If I were younger and thought I had another restoration in my future I would buy a bigger compressor unit and step up to one of the higher priced guns.
Charlie D.
 
Charlie D said:
My son bought me the Eastwood Concours spray gun with 1.2,1.4 & 1.8 tips. It is advertised to use less CFM. I have a 5hp 60 gallon compressor that pretty well keeps up with it. I generally paint only one or two panels at a time. The most I have painted at one time was the body shell of the '55 Studebaker sedan. I was almost overcome by the fumes however so I would not want to try to paint anything else that long in the garage. If I were younger and thought I had another restoration in my future I would buy a bigger compressor unit and step up to one of the higher priced guns.
Charlie D.
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I hope I am not out of line here but if you are having ANY problem at all with fumes with modern urethane paints, you are making a big mistake. These modern finishes are dangerous. Please do not spray them in a garage or anywhere else without an adequate respirator. You should not be smelling fumes. Period.

John
 
Alec Knecht said:
That was what I was afraid of. I guess I'll be in the market for a lower air consumption gun until I can acquire a larger compressor. Can anyone tell me anything about lvlp spray guns? Are they similar to hvlp but with a more efficient air cap? I've read that they have great transfer efficiency and some only require around 5cfm, but that's about all I know
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You should know that just because your compressor is inadequate for a complete paint job does not mean you can't paint small jobs, or do your vehicle a couple pieces at a time. Watch your initial pressure at the gun, and see how long it holds steady while spraying. You can still learn good gun technique with that underpowered compressor, you just have to do it one panel at a time.
 
under supply to a gun is a disaster waiting to happen. first you can not get it adjusted so you have to pile it on. bad. a certain amount of solvent disperses with atomizing . now that solvent is included in the layer of paint. add to that you are piling it on to get it wet and you are set up for solvent pop . a 3 hp compressor is for airing up ties and pool floats .
 
Thanks everybody for your input. It sucks to basically be back to square one, but I'll take it as a lesson learned. I know I won't be bettering my skills If my equipment isn't up to par. Im all too familiar with solvent pop, and I guess this could explain that in part. Charlie, how do you like the Eastwood concours? I know it's very inexpensive but has mostly good reviews. Might be a good temporary option for me until I can improve my air supply.
 
I was not crazy about the concours gun and we have plenty of air.

Where are you having trouble, basecoat, single stage or clear? If its spraying base good, then I know the answer is usually buy bigger or better stuff, but the SPI is a very heavy clear, lots of solids, it takes alot of air to move.

There are other clears on the market that are mixed 4:1:1, I dont know if anyone adds reducer to the clear here for a flow coat or not, but reducing might get your setup to spray, otherwise, you will get practice cutting and buffing.
 
It has been a good gun for me. I am using the DeVilbiss DeKups system. I have gone through about 100 cups over the past three years so I have a pretty good handle on how to set the gun up. It can lay down a nice wet coat of epoxy or single stage. Any orange peel or runs are my fault. My guess is it can spray better than I can paint. The 1.8 tip shoots SPI 2K well. The 1.4 can handle the epoxy primer and single stage. I have never shot BC/CC so I do not know how it does on those products. The Eastwood site says 4 CFM @ 30psi or so. I think with the fan opened all the way out and the volume control set at about four turns out, it uses more than the advertised CFM.

After a year and a half the gun started hissing even when the trigger was released. I contacted Eastwood technical staff and they sent me a rebuild kit which I put in but it did not stop the air leakage. They told me to mail it back and they would send me a new one. I was impressed with how they stood behind the gun. Unfortunately, a few weeks ago the same hissing has come back. I am almost through with my painting so I am going to try to get the leakage situation fixed. It does not appear to affect the performance of the gun; it just bugs me.

Charlie D.
 
At wall or compressor, try to get 125 LBs at wall or compressors than adjust for the 1.3 about 24 lbs at gun with trigger pulled.
You need the high air at wall or compressor to get the scfm you need,
 
Charlie D said:
My son bought me the Eastwood Concours spray gun with 1.2,1.4 & 1.8 tips. It is advertised to use less CFM. I have a 5hp 60 gallon compressor that pretty well keeps up with it. I generally paint only one or two panels at a time. The most I have painted at one time was the body shell of the '55 Studebaker sedan. I was almost overcome by the fumes however so I would not want to try to paint anything else that long in the garage. If I were younger and thought I had another restoration in my future I would buy a bigger compressor unit and step up to one of the higher priced guns.
Charlie D.
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I've been messing with a Concours Pro shooting primer, at 28 psi, lots of overspray, texture to the finish of the primer. Dropped it down to 15 psi, works much better. Haven't tried it with color yet. I've divided off 1 bay of my garage with plastic, cut 4 filters into the plastic, running 3 22" fans with filters for exhaust. Now I don't have any problem with the overspray and fumes evacuating.
 
imo your trying to bandaid the problem by buying a low cfm gun. any good gun will need about 14cfm. get yourself a good sata or iwata then get yourself a bigger compressor. your problems will go away. you will need a min of a true 5hp industrial compressor. in the end you will have a couple few grand wrapped up in it but youll have the good tools needed the rest of your life.
 
i little old thread but something on that startingline gun the OP mentioned:
even with the right volume of air, it doesnt atomize good and Op occured with SS and clears for me. its the nature of the gun- it doesnt atomize good.the only way i was able to get rid of OP was by over reducing and even then, there was still some OP.i stepped up to a finishline gun and that helped the OP problem some.
then stepped up to a copper tekna. no more OP problem.
 
Take a look at the 3M Accuspray, very versatile system with the variable tips and I have achieved great results with it. I second all the comments on the importance of air delivery.
 
Yossarian said:
Take a look at the 3M Accuspray, very versatile system with the variable tips and I have achieved great results with it. I second all the comments on the importance of air delivery.
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They are getting more popular, you used to be able to get them off ebay for 99.00. ummmm, real ones. I like the light weight and the fan is pretty damn big, just with any composite gun, eventually that air fitting in the bottom is going to start loosening with too much thinner getting on it.
 
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