Well the 3 stage Graco sprayer showed up last night, couldn’t convince “the man” on the 4 stage but oh well.
So I tried spraying BM Impervo oil enamel today with less the adequate results. It was splattering out a bit. Not atomizing completely. I tried a #4 and a #5 needle and thinned with penatrol. I’m not sure I can thin it much more.
what am I doing wrong?
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Replies
Is this the HVLP Graco? I've shot alot of Impervo thru an airless, but never thru an HVLP.
You do know they've come out with a latex based Impervo, and I was skeptical, but they gave me a quart at the contractors breakfast a few weeks ago, and I tried it......once it's dry, you can't tell a difference, and you don't have to wait days till it dries either.
Think I would thin with mineral spirits too.
I was looking at BM website last night and just noticed they have a water based Impervo,
Thin with Mineral spirits instead of penatrol?
Our airless is out of commision at the moment and HVLP has that new car smell so I had to give it a try.
Haven't used the Graco unit as I've got the Wagner 2600 (Capspray) turbine unit for on-site work. 3-stage - 6 psi.
I've shot latex with it numerous times using the middle-of-the-road #3 tip it comes with initially. Didn't even have to reduce to recommended spray viscosity or use any Floetrol to get a nice job out the tip. Can't quite figure why you're having trouble with that oil-base from here. Oil usually wants to atomize easily.
Are you using a viscosity cup to arrive at proper thinning or just guessing at it?
Making certain you're at or close to proper/recommended viscosity for the material in question( a chart should have come with the unit). Try starting with a #3 tip...if that's middle-of-the-road for that gun. Power up the turbine with the fluid needle completely closed on the gun. Slowly start opening the fluid needle and see if that doesn't at some point give you a good result.
(You pretty much MUST adjust the volume of material reaching the tip each time you alter the width of the spray pattern very muich at all.)
Spattering is usually a symptom of (most likely cause)too thick of material, as you indicated you understand...or the wrong tip for the absolute best results. With that oil-base at proper vis. and an MOTR tip you should get decent if not great results. But...... inadequate pressure at the fluid tip to get the job done with even the right viscosity and tip (with HVLP this can include inadequate volume of air), or feeding the material into the head too fast for the pressure and volume of air are also not unheard of.
Are you sure all parts of the gun are installed properly? Is the fluid tip seated properly in the head? Didn't manage to bend the fluid needle, did ya? :-) Is the packing around the fluid needle (where it passes thru the head to the tip) tight enough or are you leaking off air pressure and volume there. It should be tight enough to prevent leaks, but yet allow the needle to return to seat immediately when you take your finger off the trigger. A leak there could easily result in spattering of the material no matter of proper vis. and/or tip.
Is this a bleeder or non-bleeder gun? When you pull it for businees, is all the air getting diverted to the head or is some still bleeding? (Just another guess here as I've not used a bleeder gun.)
Perhaps there is something wrong with this particular turbine and it's output. Maybe not. HVLP turbine rigs are harder to get a handle on than high pressure guns. Adjustments are somewhat different and touchier as a rule. It can be quite frustrating at first. Viscosity is much touchier with HVLP as a rule than HP outfits where pressure can be adjusted to make up for other not-quite-right factors.
If you have any reason to suspect inadequate turbine pressure, see if you can get a pressure gauge rigged for attachment to the end of the hose and see what the delivered PSI really is.
Have you sprayed with conventional high pressure guns before or is this your first experience/attempts with a spray gun?
Or........bring the damn thing over and I'll have a look. No charge. :-)
PS. - That HVLP likely has a pressurized cup via the little tube running from the head to the cup. It's real easy to tip the head during spraying or cleaning or reloading and get the check valve in that line clogged with stuff. When that happens, you won't be able to get the material to feed to the head. You'll either have to remove the valve. soaking and cleaning it (lacquer thinner usually works) or replace it with a new one. I'd keep an extra on hand at all times for when it won't clean up. I've heard from guys around here that Graco is known for clogging easily on tht tube. That doesn't sound like your current problem....just a little heads-up for when it occurs and you can't figure out why no material is arriving to the head. the best way to avoid this problem is don't let the gun head tip such that material can enter that tube.
Knowledge is power, but only if applied in a timely fashion.
Edited 10/11/2003 1:46:00 PM ET by GOLDHILLER
Edited 10/11/2003 1:50:44 PM ET by GOLDHILLER
I used the cup the first time, then thinned down a bit more from there.
I'd say I'm sure all the parts are installed correctly. Nope the needle isn't bent. Not leaking any air that I can tell. Non-bleeder gun.
I've sprayed before mostly with an airless and conversion gun, This is my first time with a turbine. I wouldn't call my self very experienced, but I've never had a problem like this. This was the first time with this particular unit, and it seems everything is in proper working order.
Guess I'll just be fiddling around with a bit.
Thanks.
When you were spraying with the conversion gun...........what pressure were you running at the head? Where you down in this 6 psi range?
Reason for question.......I've known some very experienced guys accustomed to shooting HP for many years that then armed themselves with HVLP conversion guns and ran them at 35 psi!! Why? Cause they couldn't get a handle on the difference of shooting at those lower pressures. I just shook my head. What's the point of going HVLP if you're running the same pressures as before? Doh! They never did get the hang of true HVLP spraying with those conversion guns the last time we collided in their shop about 5 years ago.
Knowledge is power, but only if applied in a timely fashion.
The conversion gun was running around 8-10 psi
Qtr or Gold, what do you recommend reducing it with?
I guess I'd thin with the material recommended on the material itself....as Ort suggested. Probably mineral spirits, I would think.
I have NO experience with Penetrol as I've never had need of it (or maybe I was too dumb to realize that I did)....but my oil-based materials have always laid down and behaved just fine without it. I suppose under certain extreme temperature or outside drying windy conditions, it could and would be appropriate and beneficial. But again, I haven't any experience with it.
Edit: No offense to your experience, knowledge or alertness intended........... just trying to cover all the bases as best one can from afar..............Are you aware of the higher air temps with HVLP turbine spraying? This causes materials to build up and dry on the air cap faster than with conversion or HP spraying. The evaporative finishes seem to be the worst for this.....lacquer and shellac...but all finishes will exhibit the tendency to build around the openings of the air cap which can influence the distribution and atomization of the materials. Sometimes one can get caught off guard by this characteristic as it means you'll have to occasionally remove the air cap and clean it. On that note, other things can happen. For instance, you set up the gun failihng to get a really tight seal on the fluid tip, some material moves around the threads and invades the inside of the air cap apertures and you don't see this when you peer at the cap from the outside during those periodic visual checks. But......that now dried material is influencing the atomization and pattern the gun is producing. This can cause splattering also. The only solution of course, is to remove the air cap and clean it.
You might also want to give the cap you're using a close visual inspection to be certain it's not defectively manufactured with ill-shaped holes or holes that don't make it all the way thru.
(Again...just trying to cover all the potentials I can think of.)
Anybody experienced near you (like a cab shop) with friendly folks on board? Might want to make their acquaintance about now. :-)
Knowledge is power, but only if applied in a timely fashion.
Edited 10/11/2003 5:00:06 PM ET by GOLDHILLER
Found the problem..
Ball valve in the hose line shut off was broke and locked in a half closed position restricting to much air.
Well done. And naturally it was something that didn't occur to me as I tried to cover the bases. Obstruction of delivery hose. No matter in the end........you found it.
Is it performing okay now for your needs?
Knowledge is power, but only if applied in a timely fashion.
Quite beautifully in fact.
I even tried to spray some Everclear, BM poly acrylic today. I was expecting problems from everything I had heard from others on the acyrlic either gumming up or coming out to "hot" and drying before it made it to the surface or not being able to atomize it etc. I didn't see any of that today but I only sprayed two doors so the material wasn't in the gun long enough to gum the tip and the turbine probably wasn't on long enough to generate too much heat. The real test will be when I spray all the sashes and trim for these windows that are staring me down.
THe one thing that did come back to memory was just what a bitch it is to clean up a cup gun.
Good deal. Glad to hear you're up and runnin'.
Knowledge is power, but only if applied in a timely fashion.
Goldhiller has it covered pretty well. If you do use paint thinner for thinning, make sure it's 100% Mineral Spirits, the recycled ones won't work as well. I sometimes use naptha, if I won't a little more speed.
If you aren't used to thinning, especially for hvlp's, the recommend the use of a viscosity cup. For hvlp's, I'd guess i probably thin oil paint 10 to 15%, depending.
A coupla of things, no matter what spray systems you've used in the past, hvlp's take a little adjustment. They need to be "dialed" in tighter than most other systems. Try filling the cup with water, go out and practice watering the side of the shop or the grass, fiddle with the adjustments and see what they do.
secondly.. the hvlp, especially the cup type, needs more attention to cleaning than other systems. Since you're using low pressure, it won't back wash like high pressure systems will, which can cause problems down the road.
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Barry E
Jeff Jewitt over @ homesteadfinishing.com or the other posters have a wealth of knowledge about HVLP spraying. Its a forum worth checking out for any spray or finishing information.
Over @ knots there are also several other persons knowledgable about HVLP spraying as well. It never hurts to check those forums as well as here :)
I'm not sure what the tip sizes are with the Graco, but lose the Penetrol, thin with a proper reducer, as determined by your needs, (to be determined when you atomize correctly, and adjusted to site conditions/material), and thin the stuff more. It really is that simple; stuff too thick, or aircap too big.
G seems to know everything, listen to him.