first experience with HVLP sprayer

dfink · 12-13-2009, 04:32 PM

Well I finally decided to give a try to all the supplies I have purchased to refinish my car. I bought a cheap Menard's HVLP sprayer. Have not painted anything but wall or rattle can for 30 years then only once.
Well I managed to get paint to come out and be placed on the intended object. It will probably suffice for primer. I started with a couple of fiberglass doors I had made myself so I knew they would be rough anyhow. Spray went on pretty well but moving after done I turned around and ran into the wires hanging down from my car. Nice little mess in the nice pretty primer. Oh well I said so I go get the other door and moving it I dodged the wires but put a nice thumb print in the door while setting it down.
Well I don't know if the primer will stick to anything I intended but I can guarantee it sticks to everything else. The cleanup was the part I was dreading and probably for good reason. I did manage to get everything cleaned up but perhaps a bit on me.
Anyhow no longer a sprayer virgin which is good cause I got a lot of primin and sandin to do. When it comes time to do the actual paint to hope to score a paint booth.
Thought everyone could use a good chuckle anyhow.

962porsche · 12-14-2009, 04:05 PM

not chuckling !!! thats good ! just let things dry . may i offer one word of advice ?check and make sure all the air fittings and lines from the air compressure to your gun are all sized for hvlp . if not the hvlp gun will spray like $#!@ . a good size gun tip for primer is a 1.8 for the most part . for base an clears its a 1.3 (for the most part ) .

whiskyb · 12-14-2009, 04:21 PM

Here is a good link to setting up your gun and helping you understand the settings

HVLP Spray Gun Setup

962porsche · 12-15-2009, 03:48 AM

just one big problem with what that link states . HVLP does not work by opening up an air valve all the way to increase presure ! the name of what your using tells it all . HIGH VOLUME of air LOW PRESURE air presure!

dfink · 12-15-2009, 04:09 AM

Here is a good question. How do you pour small amount of paint from a full gallon can without pouring half on the floor. I just dipped it out with the stick for the first attempt. Took a while but only made small mess. I was thinking maybe a syringe or perhaps a soup ladel. The soup ladel you could probably use to measure. Four ladels of paint one ladel of catalyst.
What happens if you don't put in enough catalyst. Will the paint just cure slower. I think I have gun controls figured out what does what not to just find the optimal settings. That is just a matter of testing. The initial doors worked OK the primer did what it was supposed to for a first coat. That is come 95% back off. The surface was a little rough because of test spray patterns. The gun I got came with a 2.0 needle and a 1.5 needle. I am using the 2.0 for the primer. Right now I think I need to still increase the material volume so I get better initial coverage and the process doesn't take all day. The nason 2k primer I used seems to have worked pretty well. Filled what it had to but was still sandable. Also the can says pot life 1 hour so I assume I only have 1 hour after mixing the catalyst till I best be cleaning up. I would be nice to be able to have something around for longer than that. Will have to try and make sure I have enough to paint when I mix or there will be a lot of waste.

962porsche · 12-15-2009, 02:25 PM

pouring paints from a full gal. i lay a paint stick across the top of the gallon can and pour it into the mixing cup that way . pour it slow and ez let the paint run down the paint stick .you could also go to home depot and get pour spouts for gal. cans . if you don't add enough hardener (catalyst) well that depends on how much you under poured it ! but its never good ! if your spraying with the cars metal temp about 65 to 70 degrees you should be able to get the 3 to 5 coats of primer on the car in an hour with proper flash times . your first coat of primer should not be a wet cover coat . if you don't like runs then put on your first coat on medium wet . primer is not a fix it product so you should not have to pork it on . primer is for getting a uniformed finish for your top coats . your fluid tip of the gun would be a 2.0 not the needle . it on the big side but fine !

dfink · 12-18-2009, 06:46 PM

Some progress pics. Also I have determined that cheap guns may be OK but cheap regulators can cause headaches.

dfink · 12-30-2009, 07:53 PM

An update on the cheap Menard's HVLP gun. Piece O' Crap. Regulator broke 5 minutes into the first job. After the second use the anodozing is now flaking off the gun and getting into everything. By flaking I mean it about 30% missing now.
On a better note I started using the smaller tip for the primer. It goes alot slower but the results are alot smoother so you don't have to sand half the primer off just to get the primer level. I certainly can not suggest this gun to anyone. I think it was the shop pro brand.
Also still have not figured out how to accurately pour paint out of the can into the mixing cup. It is getting easier as the paint level goes down in the gallon can.

bob deluke · bob deluke's Garage

Get yourself some plastic 2 qt. paint pails, pour some paint from your 1 gal. paint into the 2 qt. widemouth bucket. Then you can better control the amount of paint you pour into your 1 qt. or 1 pint mixing cup. Nothing worse than spilling $500.00/gallon paint on the bench or floor. As far as guns go, Astro makes a good gun for about $80-90. they have different tips for primer and finish. If you are painting a lot, invest in a decent gun, DeVilbis, Binks, Sata for finish, and cheaper gun for primer. Remember to clean thoroughly after each use, especially after epoxy primer. If it hardens in the gun, you're s.o.l. Throw the gun away. Good luck with your project...

dfink · 01-04-2010, 08:46 AM

My latest problem is I get paint accumulating on what I will call the directional jet. These are the ports on the two protrusions where you adjust the direction of the pattern. Paint builds up around the holes to the point that it eventually comes off in a blob.
I am sure I just don't have something adjusted like it should be. Perhaps is because I am using a 1.4 tip for the primer instead of the large 2.0 The 1.4 is slow but I get better atomization and smoother coat of primer so I don't have to sand as much to get it flat. Perhaps I should give the 2.0 tip another go and see if I can get it adjusted better. The primer may just be too heavy for the 1.4
Also now that the paint is down a couple of inches in the can it pours pretty easy. Very little waste just what gets in the lip of the can.

962porsche · 01-04-2010, 01:43 PM

i think i recommended using a 1.8 to a 2.1 tip for your primer ? if it goes on to light and has an over spray edge on your pass across the panel when priming .then you will end up with bad adhesion with the primer . it will chip ez and may start to peal (delaminate)down the road . if the primer is going on with a little texture its ok . you have to block it for color any way . most of the time a 1.8 tip is best for primers . a 2.0 to 2.2 is best for spray fillers like featherfill .

dfink · 01-04-2010, 07:04 PM

Well I went back to the 2.0 tip. I can put on the primer quite a bit faster with the bigger tip. Must be getting a little better adjusting as I get a fairly decent finish now. It would be nice if I had the different size tips. All I have is a 1.4 and a 2.0. I hope to borrow a good gun for the final finish coat.
I still however have the paint build up problem on the sides. Not sure what adjustment will help with that. I have tried making the spray pattern shorter. I have tried making it taller. Doesn't effect much with the primer as it gets sanded anyhow but it sure wouldn't work for a finish coat.
I hate to say that I am reaching my sanding tolerance. Everyone has a sanding tolerance where they just can't sand anymore and then paint. Really good paint takes a high sanding tolerance. I have a very low sanding tolerance.

962porsche · 01-05-2010, 01:45 PM

are your spraying with all hvlp equipment ? that would be starting at the air tank to the gun . ( couplers , fittings , hoses , regulators ) if one part of your set up is not HVLP then the system will not work as it should . HVLP needs a bigger ID hose size and the fittings as well .

dfink · 01-05-2010, 02:00 PM

Air compressor is large enough doesn't really even cycle that much while spraying. It is a huge dual cylinder ingersol rand commercial compressor. You won't find this one at any hardware store. The hose could likely be larger but I don't get any significant pressure drop at the regulator. The compressor is running 120-145 and the regulator is right at the gun and is set at 45 which is the max for the gun. I think problem is likely just a crappy gun. I only get maybe a 2 lb drop at the regulator so I don't think airflow is restricted. I get a nice steady flow of air. I just don't know what to adjust to get rid of the accumulation on the side jets. I think I will try to borrow a decent gun and see how it compares.

962porsche · 01-05-2010, 06:38 PM

THE REGULAR AIR HOSES AND FITTINGS ARE TO SMALL !!!!!!! the gun only works on air volume . pressure and volume are not the same thing . you need to flow alot of air at a low pressure . what is the gun called ?HVLP ?? so untill you change your setup the gun will never work the way it should .

dfink · 01-08-2010, 10:51 AM

Yes I should probably put on all new hoses and fittings. But pressure and pressure drop and flow are related. The regulator is located at the gun there is nothing between the gun and the regulator. I am only getting 2 psi drop outlet pressure when using the gun. If I were getting a 10 or 15 lb drop or even worse then I would say the flow was restricted. The regulator may not flow enough that is a possibility. I did try the regulator at the other end of the hose and still only had a couple of lbs pressure drop on the discharge side. So again I think for this particular gun I have all the flow it can handle.
In any case I think my problem with the build up on the wings is some sort of internal leak. I tighted everything more and it was reduced. I also made some different adjustments to the gun according to the manual. Basically open the air untill you can't hear a flow change anymore open the paint valve at least 2.5 turns. I wound up quite a bit more than that. Then test the pattern. Adjust the fan, then the flow but leave the air alone. This seems to have worked the best so far.
In any case I don't learn and purchased another cheap gun. This time a harbor freight two pack. Pays to open the box and check the guns. The first one I looked at had been used, cleaned (sort of) then returned. You can buy disposable cups so that was still unused.
I will try out the new gun tonight and see how it works compared the other POS I got from Menards. The body of this gun looks like the body of some of the higher end guns with a rounded curved head that kind of drops down. The others are basically square then abruptly go to a round head. The mixing ports are also quite a bit different. Will be interesting to see if any differences. I am hopeing the new gun will deliver a bit larger pattern. The POS gun will only get about a 4" pattern

962porsche · 01-08-2010, 02:21 PM

in a word NO !! a standerd air hose can not flow the same air as an HVLP hose . putting your finger over the end of a garden hose will not make the water flow more it just gives your more pressure . its the same thing !!!!! trust me on this i was a glasurit paint tech rep for years . and i would have to but heads with cheap shop owners about this all the time . the bottom line is you need all HVLP from the air tank to the gun (every thing !!! ) or the gun will not work as it should !! is your gun working right ?? NO !

dfink · 04:35 AM

Well I tried out the new gun from harbor freight. What a huge difference. The new gun lays a very smooth heavy coat. I was able to get a very nice 9 " pattern and coverage was much heavier. I would say the time it took to cover my hood was cut to a fourth of what it was. In fact, I ran out of paint after one coat and had to mix more. The POS gun would have squeaked at least 2 thin coats out of what I had mixed. The surface was also much better and should greatly reduce sanding. If there is this much difference between these, I would love to see how a top quality gun compares. The POS gun was definately the cause of my frustration.
This gun take much more flow than the POS gun. I appear to be getting good attomization so I think the flow is OK.

J2Hanson · 01-09-2010, 06:02 PM

OK 962porsche, I've been following this and you don't mention what size hose and fittings to use. You said the complete set up should be HVLP. What size hose? I've used my Devilbis HVLP gun with success but I just feel it could be better. I'm planning on shooting my SC and so I'm trying to gather as much info (and knowledge) as I can.

Thanks!
John

962porsche · 01-10-2010, 08:55 AM

the standerd hose size is 1/4 inch an hvlp hose and fittings are 3/8 inch . i have meny devilbiss guns they work ok with standerd size air supply . but it will make a big deference changing to all hvlp . on the other hand sata's work like crap with a standerd size setup . the devilbiss GTI millennium is a good gun for the price . i have 3 that i use for base colors one is for light colors and the other two are used for medium and dark colors . most of the other time i use the sata's for clears and single stage colors .