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Conventional vs HVLP

2/23/17       
rob

I started spraying lacquer in the early 80's in my millwork business through the mid 90/s, both opaque and clears, some pre cat and conversion. From the beginning, this was a no brainer, it was intuitive, fast, easy and unscientific. Sprayed miles of the stuff with excellent results. I used a Binks 2001 in both pressure and siphon configurations, I still have both these guns. A decade later and now doing furniture in a one man shop I invested in a HVLP setup in both pressure and gravity gun, both C.A. Tech., the gravity is a Jaguar. I haven't used either in a couple of years, but am now wanting to get back into spraying lacquer. My hvlp setup is a follows: C.A. T. Jaguar with a 1.2 tip, material is Behlen’s laquer and sanding sealer 15sec through a ford 4 cup (Right out of the can). Painfully slow with fluid wide open for a large area such as a case side or table top. I have a 1.5 tip but this seems a bit large for the viscosity. I don’t seem to be able to get the same quality of atomization and speed from the HVLP as the conventional guns. They also seem to require more fine-tuning for a given application. I do this on such a small scale I could care less about transfer efficiency among other things, just interested in ease of use and quality of finish. I am close to ditching the HVLP guns and dusting off the old Binks 2001’s… Any advice here would be appreciated.

2/23/17       #2: Conventional vs HVLP ...
Leo G

I'd use a 1.7 tip. You need to have hi flo fittings and make sure you enough CFM to use that particular gun.

2/24/17       #3: Conventional vs HVLP ...
kevin

i personally would never use a 1.2 tip for anything. I always go with 1.8 and dial it back if needed.
Why use a small nozzle that cant be opened up instead of a larger nozzle that can always be restricted?

2/24/17       #4: Conventional vs HVLP ...
rob

Thanks for the advice, I will try the larger tip. The 1.2 was recommended by the manufacturer based on the viscosity of the lacquer I am spraying. Based on what I am experiencing I'd say you two are correct. Thank you.

2/24/17       #5: Conventional vs HVLP ...
Jim Clark

Most HVLP guns spray better if you crank
up the PSI a little.

If you run higher pressure, like 70 PSI
to the gun and then regulate down with a
pressure regulator at the gun, you can
overcome the small fittings pressure
loss issues.

2/24/17       #6: Conventional vs HVLP ...
Nick

The Jaguar is a gravity gun right? when compared to a pressure set-up a gravity gun's fluid flow is slow...very slow. so if you used a 1.2 on your 2001 use a 1.7 on the jaguar to get comprable results. even at that it could still be a bit slower.
air volume is the key to good results with hvlp. so change out your connection fittings to high flow and make sure your compressor has the cfm to match or exceed the needs of your gun. Or just go back to the 2001. The 2001 is a great spray gun; pretty fast and a flawless finish.

2/24/17       #7: Conventional vs HVLP ...
Arthur grudko

Be aware that the transfer efficiency of the average HVLP sprayer is greater than 90%, and your Binks guns is around 20%. If you can afford the waste of finish and the more rapid changing of filters of the spray booth, then go with the Binks. If saving money is important, then it's worth climbing the learning curve for HVLP. If properly adjusted, the HVLP system will put out as fine a spray as the conventional.

2/24/17       #8: Conventional vs HVLP ...
Nick

To my understanding Arthur is both overstating and understating.
my understanding is most HVLP spray guns have a transfer rate in the 70-75% area and to meet the HVLP standard need to have at least a 65% transfer rate and have no more than 10 psi of air pressure at the cap. Many HVLP spray guns end up compromising speed and quality to achieve this standard. also it is my understanding conventional spray guns have a transfer rate around 30- 40%. that is still close to 1/2 as good and a good reason to go with something with a better rate. Of course it still depends on how you use either one. crank up the pressure on either one and you'll produce more overspray and of course use more compressed air.

2/24/17       #9: Conventional vs HVLP ...
rob

Your post, Nick, came in as I was beginning this reply. The research I have done on conventional vs HVLP transfer efficiency is more in line with your numbers. When I owned and operated a small custom millwork and cabined shop this would have been an important issue. As I now have the luxury of a one man well equipped shop building mostly one off furniture, not so much. Speed, ease of use and quality of finish are primary at this late stage of my career. It just seems that to get the same results, the tuning of the HVLP guns is a bit more dicey. By the way , my compressor capacity is not an issue.
I have at this point four quality guns, 1 pressure and 1 gravity HVLP (C.A. Technologies). And 2 Binks 2001’s one gravity and one pressure. So I will continue to work the learning curve as Arthur suggested to see if I can obtain the same results with the modern guns, but will put the older Binks back into use as well.
With that said. Thanks to all for the professional and useful advice I have received so far. Any further examples of setups by those experienced with this equipment is much appreciated.
Couple more questions.
I get the impression that exceeding the rated air pressure on the HVLP guns is pretty common to get better atomization. Is this the case in the field?
I work mostly in Cherry and go to great lengths to select for grain and color to avoid coloring the wood. Lately though, I have been playing with transtint dyes to shift the color slightly to blend everything in and to warm the piece up a bit until the natural aging takes over. A total of 1 teaspoon of dye combination in 12 oz thinner and 2 oz of lacquer sprayed over a washcoat of de-waxed shellac seemed to work. What would be the ideal gun setup for this.

Regards
Rob

2/24/17       #10: Conventional vs HVLP ...
Arthur grudko

Nick, I stand corrected. The savings/efficiency differences are likely not as pronounced as I thought. They are more in line with your figures.

Is there a difference between a compressor driven HVLP conversion gun and a turbine system? I have both, and seem to get more efficiency and better spray results from a turbine sprayer.

When I had a Binks Mach 1 HVLP setup with separate air pressure for the cup and the gun, I got excellent flow and leveling with minimum overspray. The set was so heavy, I gave it up for a turbine system and got the same results.

2/25/17       #11: Conventional vs HVLP ...
afinisher

I use 2 pressure pots for lacquer work. I fought with conversion hvlp guns starting in the early 90s and it wasn't till high efficiency guns came out around Y2K that I was finally ready to retire my binks 62.

High Efficiency or Reduced Pressure technology gives you the speed/material flow and atomization comparable with conventional with much less overspray. I've been very happy with this Devilbiss gun. If you look into it be sure to note you are looking for high efficiency air cap- not HVLP. The HVLP version is the same gun but with a different air cap.

Devilbiss Transtech High Efficiency Gun

2/25/17       #12: Conventional vs HVLP ...
kevin

Rob, to spray a toner such as your describing i use a gravity feed hvlp. Easy to dial in a small stripe if needed to blend in problem areas. Once you get tuned in with your equipment, it becomes an extension of your arm.

2/25/17       #13: Conventional vs HVLP ...
nick

I agree with afinisher on both counts; the devilbiss compact with the reduced pressure/transtech air cap is a is a very good spray gun ( the Binks Trophy LVMP is very similar) and I prefer reduced pressure aircaps/spray guns over HVLP ones; they are usually faster with better atomization, use less air and still deliver very good transfer rates...what's not to like?


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