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Old 09-17-2011, 04:27 PM
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Default Spray Equipment: Air powered conventional/HVLP vs. Turbine HVLP vs. Airless vs. AAA

I have been using traditional lacquer for several years now and have used only conventional air guns to spray it. I started with Binks 2001 copies and have switched to using an Iwata HVLP with a pressure pot. The pressure pot doesn't make much difference but that I don't have to keep filling my cup all the time. The Iwata is a nice air powered gun and I'm pleased with the results.

But now, please school me on the differences and what to expect if I switch to:

1. Turbine HVLP
2. Airless
3. Air Assisted Airless

I spray instruments so I don't need fast huge area coverage. I use a full size conventional air powered gun right now and I like the control I have with that speed. I don't like touchup guns. But I don't want something designed to spray a barn either. So... that's the background. I spray a glass level table top style finish built from several thinned and wet coats of lacquer with my current air powered guns.


Now, the reason I'm even asking this:
The PDS and the can of most lacquers by almost all major manufacturers mentions Airless as the first/preferred method for applying the product. It seems that most lacquer manufacturers design product viscosity with Airless in mind and some don't even mention conventional guns in their application data sheets. I use the lacquer in my conventional/air powered equipment, BUT I have to thin it at least 50/50 or I get solvent pop (bubbles) with a coat wet enough to flow out.

Curious if I should make a switch. I don't like thinning if I don't have to. That wastes thinner (it is like evaporating my money with every bit of thinner I add), it also requires more coats to get the required film thickness, less coats = less spraying time, I'd also guess it takes longer to cure since more solvent (from the thinner) has to leave before it's cured. Lastly, adding thinner messes with the formulation of the lacquer and I don't like that either.

I'm curious what you guys have experienced in spraying?

EDIT: I should add this is for CLEAR coating only. I am looking for a good system for clears. I will still use regular guns for colors/tinting/shading.

Last edited by NickSorenson; 09-17-2011 at 06:19 PM.
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Old 09-17-2011, 04:57 PM
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Default Re: Spray Equipment: Air powered conventional/HVLP vs. Turbine HVLP vs. Airless vs. A

I do both conventional and HVLP. An airless unit, IMHO, would only be
applicable for production runs and you need to develop a different touch
than that of conventional cup guns. Also you have all that product in the
hose to deal with at some point in the process. If you are asked to use
a conversion or catalyzed product with a limited potlife, that means you have to clean the hoses right after you are done spraying. The HVLP is portable and you don't have to worry about moisture in the lines. My experience is that the conventional will leave a smoother finish on average but not always. If your wet sanding and buffing out the finish than that isn't much of an issue. If you go with the HVLP buy the cleaning kit that
goes with it.

Thanks
Matthew
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Old 09-17-2011, 05:33 PM
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Default Re: Spray Equipment: Air powered conventional/HVLP vs. Turbine HVLP vs. Airless vs. A

I think the lacquer manufacturers suggest airless so they're responsible for fewer VOCs in the air (since you don't need to thin for airless).

For spraying instruments filling a 25 foot hose with lacquer seems crazy.

I'd go with a gravity fed HVLC since I don't like a lot of VOCs in the air either. Gravity fed since you don't need much volume per coat time for instruments and clean up is simpler.

For spraying clear coats I use HVLC (an old Apollo 3 stage turbine).


I'm currently researching airless sprayers for latex paint. I like the idea of air assisted airless as a combo unit but good ones cost $$$$. March of 2010 I got suckered into buying a cheap new combo unit that Milwaukee put out. It has a well speced DIY grade airless pump and a 2 stage turbine and a combo gun. Set it up to spray latex a couple days ago and it wouldn't prime. In the shop for warranty "repair" for an indefinite period of time.

That problem got me to look into the subject and found that for air assisted airless you need a pump with electronic pressure control (to minimize the on/off pressure differential) to minimize the spray pattern size change. In air assisted mode you have the pump pressure fairly low 700 to 1000 psi and with a lower end pump the deadband (on/off pressure differential) might be 500 psi so there can be a huge difference in pattern size and even atomization.

Now I'm looking for the lowest cost electronic pressure controlled airless pump to pair with my Apollo sprayer as an air assisted rig. Any ideas out there?

Another option which I'm leaning towards is to get another 3 stage turbine and run them parallel. With a 2mm or larger tip my current HVLC gun should be able to spray latex with little thinning.
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Old 09-17-2011, 06:03 PM
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Default Re: Spray Equipment: Air powered conventional/HVLP vs. Turbine HVLP vs. Airless vs. A

I won't use anything but an airless for lacquer. I once let someone convince me to use a conversion gun on a project I was editing for American Woodworker Magazine and that was the last time.

When you have to thin the material, you also make it more prone for runs. The airless delivers nothing but product to the surface, whereas the air driven delivery is putting more air than product at the surface. This air has to go somewhere. It bounces off the surface of the workpiece, and with it, it carries the VOC and product with it. There always seems to be comments saying airless sprayers produce more over-spray, and I have no idea where this myth got started. It's completely the opposite, and anyone that has spent time using both type will tell you that.

Because nothing but product is being delivered, the build is much higher and faster. For a high build, I shoot one coat sanding sealer and one or two coats of top coat. Anything after the first top coat is just to get a better surface. There is no need to apply more coats solely for build.

The trigger and spray tip are the most crucial parts to an airless. The pump doesn't need to be top of the line to produce a good finish. This means you can get into an airless system without breaking the bank, but spend the extra money on good quality tips. For your small pieces, use a finer tip with a lower pressure. There are even tips that are adjustable.
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Old 09-17-2011, 06:12 PM
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Default Re: Spray Equipment: Air powered conventional/HVLP vs. Turbine HVLP vs. Airless vs. A

Quote:
Originally Posted by RickChristopherson View Post
I won't use anything but an airless for lacquer. I once let someone convince me to use a conversion gun on a project I was editing for American Woodworker Magazine and that was the last time.

When you have to thin the material, you also make it more prone for runs. The airless delivers nothing but product to the surface, whereas the air driven delivery is putting more air than product at the surface. This air has to go somewhere. It bounces off the surface of the workpiece, and with it, it carries the VOC and product with it. There always seems to be comments saying airless sprayers produce more over-spray, and I have no idea where this myth got started. It's completely the opposite, and anyone that has spent time using both type will tell you that.

Because nothing but product is being delivered, the build is much higher and faster. For a high build, I shoot one coat sanding sealer and one or two coats of top coat. Anything after the first top coat is just to get a better surface. There is no need to apply more coats solely for build.

The trigger and spray tip are the most crucial parts to an airless. The pump doesn't need to be top of the line to produce a good finish. This means you can get into an airless system without breaking the bank, but spend the extra money on good quality tips. For your small pieces, use a finer tip with a lower pressure. There are even tips that are adjustable.
Thanks for the feedback. What about cleanup? I use ONLY conventional (non catalyzed) lacquer. If I always keep the gun and hoses (entire system) loaded with product would I need to cleanup assuming I spray every few days? I rarely clean my current pressure pot system's gun and hoses. I just keep them full of lacquer, brush off the residue on the tip and keep spraying the next day.

I'm thinking of trying a cheap Airless or Turbine just to see but I'd hate to get a bad impression from junk.

In Air Assisted Airless, would the advantage be a better atomization and less orange peel (easier flow-out)?

One thing I DON'T like about Airless is that it's a stinger (pickup) dropped in a bucket. I don't leave my lacquer gallons uncapped for various reason including:
1. cleanliness-I don't want the lacquer coming out of the bucket (i.e. spilling on the floor) and I don't want debris landing in my clear lacquer.
2. evaporation-I use a pressure pot (sealed) and I don't get much evaporation or film skimover on the top. If I left it open, I'd get both.

So, I need a sealed system to put the material in. Would I have this possibility with Airless or AAA?

Last edited by NickSorenson; 09-17-2011 at 06:15 PM.
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Old 09-17-2011, 06:25 PM
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Default Re: Spray Equipment: Air powered conventional/HVLP vs. Turbine HVLP vs. Airless vs. A

Because it's a sealed system, you can leave your lines charged for months. The only time I ever flushed a line was as I was switching between sealer and top coat, and I would use the next finish to flush the previous one out. I didn't even bother cleaning my tips most of the time. I simply reverse the tip so fluid flowed backward and let the high pressure lacquer purge the old. Of course I did periodically drop the tips into a jar of thinner, though.

I am not familiar with air assisted, but my first reaction is that it is a gimmick that was created for people believing some of the misinformation about airless. The added air does not atomize the product. That is done at the spray tip. Orange peel is caused when the product has partially dried before it hits the surface. The addition of air would increase this, not decrease it.

Not all airless systems use a stinger. I wish I hadn't sold it to my dad, but I originally owned a hopper feed sprayer that would be more effective these days because I don't spray as much as I use to. However, your finish won't evaporate very much while you are spraying, so that isn't really an issue. The lacquer vapor is heavier than air, so the top of the can will be lacquer vapor, not air.
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Old 09-17-2011, 08:08 PM
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Default Re: Spray Equipment: Air powered conventional/HVLP vs. Turbine HVLP vs. Airless vs. A

I don't understand why HVLC is rated as having less overspray than airless either but what can you go by other than anecdotal testimony and industry literature? It's pretty much impossible to compare apples to apples. You'd have to have the best guns and tips for each system and they all cost hundreds of dollars each.

So I just do a lot of reading. One example of the anecdotal testimony: paraphrased....a guy bought a good HVLP outfit and loaned it to a friend with a good conventional spray outfit. The friend sprayed one side of a door with one kit and later sprayed the other side with the other kit. Both sides looked great. The guys were shocked to find half as much material left in the conventional cup as was left in the HVLP cup. Presumably they'd both been filled to the same level to start.

I've never used conventional spray guns myself but I've watched an expert spray in a very high end spray booth. There was a lot of overspray but it was well managed by the booth. I didn't have the means or space for even a crappy booth so I went for HVLC. Even so, I was kinda shocked by how much overspray there was at first. Turns out I was using too much air.

Graco has a new line of "Fine Finish Tips" for their airless sprayers. Small orifices and narrow fan patterns. They fit the RAC X tip. Graco also has a hopper accessory that can replace the stinger.
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Old 09-17-2011, 08:13 PM
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Default Re: Spray Equipment: Air powered conventional/HVLP vs. Turbine HVLP vs. Airless vs. A

There's a lot of good gouge up there so far. I would not go with the air assisted. There's just no need for the extra components.
Now, I don't know what you're doing, but if it is all small stuff, then I like the gravity fed gun idea. Especially if you can get away with a touchup style gun. I've used good and bad. The bad are horrible, messy, and create a fog. The good ones, the really good ones, are dreams.
A good quality conversion gun, set and dialed in properly, should give you virtually no overspray and not require you to thin. You change the needle and the cap for different viscosity fluids.
For bigger projects, airless is fine. I absolutely agree with monstrol that if what you are used to is a conventional style cup gun, switching to an airless is going to take a few test runs on scrap. If the conventional delivers fluid like the kitchen faucet, the airless delivers it like a fire hydrant.
If you are looking at that, you do not need a huge setup. The smaller, but professional grade machines like the Graco 395 are perfect. And you also do not have to use the "bunny ear" tips like you would for latex. There are lacquer or "flat" tips which, for lacquer, deliver a great finish with a lot less overspray.
I would also invest in a 3-5ft lacquer rated whip for the hose end. This gets the last few feet of hose smaller diameter and a lot more flexible, letting you get the gun more places, with less fatigue, and more control.
I also have a pressure pot and that is ok for some things. I actually prefer it for waterborne coatings, but the twin hoses do present a challenge if you're going to be using it for a long time. It wears on you. And it takes some effort to make sure the lines are good and clean when you're done.
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Old 09-17-2011, 10:41 PM
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Default Re: Spray Equipment: Air powered conventional/HVLP vs. Turbine HVLP vs. Airless vs. A

I've been reading about multi-stage vacuum /blower motors, the things that power better vacuums like Festool and Miele, and particularly HVLP turbines.

Apollo was one of the very first manufacturers of HVLP turbines and they make a point of using "...the best quality, all aluminum, ball-bearing motors, manufactured in the USA by Ametek-Lamb."

When looking at blower motor supply catalogs I often saw Ametek-Lamb motors listed as being made in Mexico. And then I found this:

"One of the oldest, largest American motor companies in the world, located in the good ol' USA. Their motors have stood the test of time and have an impeccable reputation, and we still believe their motors are rock-solid. They've always been favored in the central vacuum field.

"Within the past 5 years, competition has given them (Ametek-Lamb) a run for their money. Because of the general decline in the U.S. economy, they've had to relocate some of their factories to Mexico. When we spoke with them last, our jaw dropped after finding out even WORSE information. They are transferring the majority of their production facilities over to China soon. What happened to being built in the good ol' USA? It's because labor over seas is cheaper than it is here."

If you go to that link you'll have to scroll down to the second or third article to get to the Ametek-Lamb bit. You'll have to go past the article that announces that the company (ThinkVacuums) has signed on to be the exclusive US distributer of the Domel, the German manufacturer of blower motors that is kicking Ametek-Lamb's butte.

Are manufacturing wages in Germany really lower than wages here? Or is something wrong with the administration of manufacturing companies here?
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Old 09-24-2011, 07:40 PM
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Default Re: Spray Equipment: Air powered conventional/HVLP vs. Turbine HVLP vs. Airless vs. A



Nick, where are you in your search for a new spray system?

Heating the product will reduce the viscosity of almost anything and you can add the Kremlin heater to a pressure pot system but for a small shop that already has an air compressor I think a gravity fed HVLC gun is most appropriate. You can also put a small pressure pot in a double boiler like Phillip said.

Spend several $$$ on a great gun and a couple $$$ more on a variety of fluid projector sets (or just get two guns if you only use two viscosity materials). Gravity fed is good for your scale because with anything else you'll spend way more time cleaning up than spraying. DeVilbiss has a disposable gravity fed cup system, (DeKUPS) similar to the 3M cup system. Not sure if 3M has a gravity feed version.
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