Praise for HVLP
Has HVLP outgrown a bad reputation? Here's why some swear by it. (Finishing Forum) May 19, 2003
Question
I hear an awful lot about HVLP these days. Why should I convert to it from a traditional air gun? Only a few states require it by law. People say it has reduced quality and slows you down.
Forum Responses
(Finishing Forum)
From contributor A:
Here are some of the advantages of HVLP:
1. Drastically less overspray. You can save 60%-70% of paint costs.
2. Less replacement of filters on your exhaust fan and respirator.
3. Superior off-the-gun finish.
Huh? That's right. A well-selected, properly designed HVLP gun sprays better than conventional. Early HVLPs were just conventionals with restrictors, giving poor results. If an HVLP is designed from the ground up by someone who isn't bound by conventional gun engineering thinking, it will spray better than any conventional gun.
Check out some of the new guns from Turbinaire, Binks, DeVilbiss, Asturo, etc. Take the time to set the gun up properly with the right air cap, nozzle and needle. The money you spend will be quickly recovered by using drastically less finish.
I am with the above post. My Accuspray gun is the best spray gun of any type that I have ever used. My turbine will fit on the floor of my truck cab and still leave room for the gun, hose, and some paint. Overspray is dangerous and a quality control problem. The HVLP system reduces it amazingly. You couldn't give me a standard spray system of any level of quality. To me they are just trash. I can spray most materials as fast as I want to, though my focus is more on quality than speed.
From contributor B:
Nothing, and I mean nothing, sprays finish better than a conventional gun. Period. That's if you can live with the overspray, don't care about the cost per gallon, etc. Try shading with HVLP. There is a place for both types in my shop and I do have all types. I still use my Accuspray for primers (if a small job), cheap conventional gravity for shading and one-off jobs, and A/A for everything else. No one gun (spray or bullet) does everything great.
What is most important to you: being portable, fast, easy to clean, top quality spray, easy to get parts, works with most finish? The first response gave good info but you have to consider your own conditions. For example, I don't use a turbine system anymore because the heat from the air gun gets too hot. It seems that you have to keep adjusting your gun to compensate for that heat change and I don't have to leave my shop. I have a 5 hp, 80 gallon compressor, so I use a conversion gun. It works better for me - less overspray and once you start, you're spraying, not adjusting. I think that some of the turbines have this problem under control. You should demo some find one that works for you. Also, if you don't have a compressor, I recommend putting some money into one before a turbine, unless you need to be portable.
From contributor A:
Can't figure out why contributor B has a problem with shading and HVLP. I do shading all the time on pianos, a very critical application, with HVLP. No problem. Maybe he got stung, as so many did, with early HVLP guns that were merely conventional guns with restrictors. Try a new, well-designed one. They do everything conventional does without the overspray and waste.
Turbine vs. compressor HVLP is a good topic. I've got both, and depending on the sensitivity of your coating to heat, it's almost a tossup.
Turbine air is always dry, but warm. This can be good on humid days with NC lacquer (reducing blushing), but can cause an adjustment problem, as pointed out above. If you turn it on for a few minutes to let it warm up before spraying, this should take care of that problem.
However, turbines are noisy. Then again, compressors aren't exactly quiet either. You have to have good filtering for oil and water on a compressor, but not a turbine. Compressed air is always available at the gun, but you have to turn on the turbine every time you spray, unless you have a remote switch.
Other than changing the air filters occasionally, there's no maintenance on a turbine. You can't operate air tools on a turbine, but turbines are small and portable.
I wish I knew why some days I use the turbine, and some days I use the compressor.
I have been considering the purchase of an Axis 4 stage turbine unit with an Accuspray Model #10 gravity fed gun. Can I get feedback ?
Though I'm not familiar with your setup, I would think that a 4 stage turbine is overkill unless you can "turn it down." It would be very difficult to do any touchup or fine detail with all that air blowing out the gun. I have an Apollo 1200 with both 2 stage and 3 stage turbines. I can use the 2 stage for stains or touchup, 3 stage for sealer or thin finishes and both together for unthinned topcoats. I'm sure the 4 stage unit would give excellent atomization for your finishes.
From the original questioner:
Thanks for the input. I have plenty of compressors so I am leaning to a top feed for easy cleanup. May have to get the filling station to make the larger jobs easier during refills. Planning on spraying urethanes and lacquers.
We like the conventional compliant guns over HVLP. You use less CFM, good for woodworkers with smaller compressors. You get a faster production speed. You get 65% transfer efficiency and better atomization. Conventional compliant is great.
I had a cabinet shop in LA where HVLP was mandated by the AQMD many years ago. It was originally pitched to the District by a snake-oil-selling turbine company that claimed it could work wonders. The district also bit on 111-Trichoroethane as a wonder solvent about the same time.
Unfortunately, finishing is a system, not a gun. It involves equipment, material, people and weather. If all the elements are not working together, the system doesn't work well.
We found our people were more likely to thin or retard material than adjust fluid tips and air caps, and no one ever used a Zahn cup or talked about viscosity. There were a lot of habits that had to be overcome.
For a long time HVLP was not suited to use with high solids material, but an air assisted HVLP properly configured can work okay.
Over time, our people got with the program. HVLP can work well with most materials if the operator takes the time to make the adjustments to materials and the gun to get it to work properly.
Is there one HVLP that somebody would recommend for spraying varnish on cabinets, spraying oil based enamels, and latex house paint? Cost is not a big factor. Also, what about clean up? I know some units come with 50 feet of hose - too much to clean up for smaller jobs!
I don't think that anyone will recommend HVLP for spraying latex house paint. Most HVLP systems are cup guns in which the hose only carries air and needs no clean up. Accuspray is about tops in the turbine guns. A lot of guys like the conversion guns (which run from compressors) in preference to the turbine guns. I love my Accuspray.
I bought a Devilbiss Finishline HVLP compressor gun, cup style, several years ago. I do a wide variety of projects that include finish carpentry and cabinetmaking, and in my spare time I restore vintage motorcycles. Out on the job site sometimes a good supply of electricity is hard to come by. I looked for a compressor that would provide the power I needed to run nail guns and tools without blowing breakers or fuses. I chose a Speedaire 1 1/2hp with a 30 gallon tank. This unit does not keep up with my gun if I am using it non-stop. I have to take a short break now and then to let it catch up. Although it only uses 23#psi it does use a large volume of air. The first job I did with it was a long fancy fence with acrylic. It worked great. Very little overspray and direct application right where I wanted it. I use the same gun and air cap for oil varnishes, NC lacquers, latex, waterbornes as well as House of Color Cat polys in pearls and metalics. I don't have to be concerned with viscosity. It applies all finishes very well right from the can with only slight adjustments to the air and material screws. I have not used a turbine - too expensive and I do not want to lug a garden hose around. I just plug my gun into a 100 ft. air hose and go where I want. Don't expect a pancake compressor to do the job, not enough volume. I rank the gun as one of my best purchases.
