HVLP? (High Volume Low Pressure)

Is this a method of spraying lacquer that would work well with Ukuleles??

High Volume Low Pressure....
It sounded really close to a vacuum cleaner and the hose that hooked up to the spray gun looked like a vacuum hose.
I spoke with a guy I know that rebuilds tube am radios...
The old ones with the wooden cabinets from the 30s and 40s..
He was spraying lacquer on one of those "tombstone" style radio cabinets in his garage and the days temp was probably 53 degrees Fahrenheit at the most.. Overcast skies.. I asked him if he had good success with spraying in those kind of conditions and he said because of the delivery method it worked great... Also he said that when he used to use his regular air compressor he would over whelm his garage with the spray.. it would get everywhere.. With the HVLP system its not a problem and he doesnt have to worry about the over spray as much.
In my limited experience Ive always used Nitro from a can.. and last year had horrible results once the temps started dipping..
He said the HVLP system gave him a super fine mist and he didnt have any issues with spitting..... Anyway.. I was wondering if anyone here has had experience with that method of application???
Thanks for any comments..

It really would depend on the HVLP system. Some are much better than others, and if this fellow is spraying with lacquer and it's working a treat for him, then that's most likely a system to look at. Unless they have dropped in price considerably then they are going to be a sizable investment. Last ones I saw were $1,500+ but they were designed for automotive spray booths, where I worked for 35 years. We had plenty of systems demo'd over the years, but none where up to snuff for the job we needed them to do.

Turbine systems like the one you saw by their nature supply air that is warm, so if you are spraying in cooler conditions, this can be ideal. All they are doing is moving air and it gets heated up by the turbine action. In hot conditons though you are really going to struggle as your product is going to be drying the split second it's out of the nozzel.

Compressors act in a different way and supply compressed air that heats up as it's being compressed and cools as it expands out where it's needed. You have a lot more control of that supplied pressure and this is useful for all kinds of things.

Each has it's merits, but for me the only one to choose if you are going to spray something like ukuleles is the compressor and small HVLP gravity feed gun.

Compressed air is used so much in the workshop it would be like loosing an arm with out it there when needed. You just don't have that with a turbine system. However if money is no object, then you could get both the turbine and a compressor.

Thanks Allen,

That really explains alot.. It makes sense why he would be able to spray in cooler temps with a heating of the air by the compressor... I was heating up my cans of nitro in a warm water bath
So they wouldnt spit last fall when the temps started dropping and that has its inherit problems.. So I struggled just trying to finish up the myrtlewood I was working on..
I was intrigued when I saw my friend spraying yesterday due to my own limited experience..
I believe he was using a cheap unit from Harbor Freight... Maybe 100 dollars.. So its along way down from what you were describing at 1500.
I didnt inspect the finishes on his radio cases very closely, from my vantage they looked good.
I like the idea of having a couple of different options as you stated using a compressor and a small HVLP gravity feed gun..then also having a small HVLP compressor for when the temps start to drop.
Im dont believe I will ever be doing this on a large scale but I would like to do it the most efficient way I could find that works the best.
Every time that can would spit on my Uke Id have a fit.. waiting for it to dry and sanding it again... It was like taking a step forward and 3 steps back..
I had a friend that was working on his tenor and he was french polishing and I thought that was another option,,,, I had tryed it but,, I had even more trouble with it..
Ill have to get some books and media on it I guess..
The folks here on the forums sure helped on that topic in a different thread which helped tremendously..
Thanks for the info Allen. It makes total sense to me now.

I've used a Fuji Q4, four stage turbine, for the past 10 years and much prefer it over compressed air. I don't have to worry about contamination or traps and as your friend mentioned the air around you is MIUCH cleaner. It sprays lacquer onto the object and not in the air, which also results in savings. I regularly spray in temperatures of about 80 to 85 degrees with no problems. Of course your material has to be thinned properly and I do add 5% retarder to my mix. You can also bring down the temperature of the fed air by doubling the length of the hose but I've never found that to be necessary. HVLP is not good for applying sunbursts as the particle size is too big but other than that it's the perfect machine for me. I wouldn't waste my time on anything less than 4 stages, they just aren't powerful enough to atomize properly. And to can get quieter machines; the "Q" in my Fuji Q4 stands for "quiet". I will probably upgrade to their 5 stage if and when my current one ever quits on me. But so far I have not had a single problem after spraying many hundreds of ukes.

I'm only a few miles from Chuck, but with much cooler and wetter spray conditions. Been using HVLP for 20 years. On my 4th HVLP system and my 2nd Fuji system now. They are very good. Still using a 3 stage system, with no complaints, but maybe if I tried a 4 stage I would like it better. The main differences between Fuji systems is the type of gun you use. I switched from a cup gun, of which I have 2, to a gravity feed. The cup feed gun is far easier to clean and refill, but the gravity feed is light years ahead of it in the quality of the finish. I resisted gravity feed for years, but would never go back to a cup. Maybe that extra 4th stage helps with the gun type, but for lesser systems I would highly recommend gravity feed.

Moore Bettah Ukuleles said:

I've used a Fuji Q4, four stage turbine, for the past 10 years and much prefer it over compressed air. I don't have to worry about contamination or traps and as your friend mentioned the air around you is MIUCH cleaner. It sprays lacquer onto the object and not in the air, which also results in savings. I regularly spray in temperatures of about 80 to 85 degrees with no problems. Of course your material has to be thinned properly and I do add 5% retarder to my mix. You can also bring down the temperature of the fed air by doubling the length of the hose but I've never found that to be necessary. HVLP is not good for applying sunbursts as the particle size is too big but other than that it's the perfect machine for me. I wouldn't waste my time on anything less than 4 stages, they just aren't powerful enough to atomize properly. And to can get quieter machines; the "Q" in my Fuji Q4 stands for "quiet". I will probably upgrade to their 5 stage if and when my current one ever quits on me. But so far I have not had a single problem after spraying many hundreds of ukes.

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Thanks Chuck,
I truly appreciate the information as I dont have enough experience to know any of what You and Alan have shared..
I dont think I will ever be applying sunbursts at this point so I would probably get away with not needing that application.
The problem I have here in Eastern Washington is the fall, winter and spring.. I have a very small shop and if I spray, its outside... So part of fall, all of winter and part of the spring is a no go for me.
In my musing it all over I thought that French Polish would solve it but I think that will take alot more research and practice.. and Im sure it has it place but when I can spray, Id like to try the HVLP system and the fact that the turbine heats the air is a plus to me in the cooler temps.

UkulelesRcooL said:

Thanks Chuck,
I truly appreciate the information as I dont have enough experience to know any of what You and Alan have shared..
I dont think I will ever be applying sunbursts at this point so I would probably get away with not needing that application.
The problem I have here in Eastern Washington is the fall, winter and spring.. I have a very small shop and if I spray, its outside... So part of fall, all of winter and part of the spring is a no go for me.
In my musing it all over I thought that French Polish would solve it but I think that will take alot more research and practice.. and Im sure it has it place but when I can spray, Id like to try the HVLP system and the fact that the turbine heats the air is a plus to me in the cooler temps.

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As I've mentioned, the heated air produced by HVLP has never been a problem for me even when spraying at 85 degrees F and would probably be helpful to you in spraying in cooler temps. Much of the success in spraying with any equipment, but HVLP specifically, is in knowing your mix. Because the particulate size is much bigger than with compressed air systems it will produce an orange peel surface more readily if you don't thin properly. A 50/50 mix is not too thin. (In my particular case with the lacquer I use I mix 50% lacquer, 45% thinner and 5% retarder.) It lays on very nicely and flat with minimal orange peel. Using the smallest tip available;ab;e is important as well. Again, I warn you not to be tempted by anything less than 4 stages. I used a 3 stage before buying my Fuji Q4 and it's a world of difference. BTW, if you are spraying outside your neighbors will thank you. No more nasty vapor clouds in the air. It does make noise though but that's why I got the "quiet" version. (I have no neighbors anyway.)

Pegasus Guitars said:

I'm only a few miles from Chuck, but with much cooler and wetter spray conditions. Been using HVLP for 20 years. On my 4th HVLP system and my 2nd Fuji system now. They are very good. Still using a 3 stage system, with no complaints, but maybe if I tried a 4 stage I would like it better. The main differences between Fuji systems is the type of gun you use. I switched from a cup gun, of which I have 2, to a gravity feed. The cup feed gun is far easier to clean and refill, but the gravity feed is light years ahead of it in the quality of the finish. I resisted gravity feed for years, but would never go back to a cup. Maybe that extra 4th stage helps with the gun type, but for lesser systems I would highly recommend gravity feed.

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Thanks for your input.. I appreciate all your advice and information.. I know you guys know what your doing and it helps me from making blunders that Ill regret later..

UkulelesRcooL said:

I know you guys know what your doing and it helps me from making blunders that Ill regret later..

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Don't count on it, you'll still make you share of blunders. Finishing is an art more than a science. I can advise 10 different builders on how to finish an uke and they'll all have somewhat different results. Besides, if you aren't making mistakes you're not trying hard enough!

I've been using a DeVilbiss touch up gun for a couple of years now but the Fuji 4 stage is in my immediate future.
The Q model is probably out of my range but I want the 4 stage turbine for sure

i use iwata HVLP guns driven by a regular compressor. these are more or less what the auto body guys use and are top of the line.
if you have a good electrical supply, not all shops do, you are well served by bleeding for a legitimate compressor, and whatever piping, aftercooler, and moisture traps you will need. you then have the industrial heart of any shop and can run d/a air sanders and normal spray guns.
a lot of money is spend avoiding getting a legit compressor, in specialized sanding and spraying equipment. to each their own.

Moore Bettah Ukuleles said:

Finishing is an art more than a science. I can advise 10 different builders on how to finish an uke and they'll all have somewhat different results. Besides, if you aren't making mistakes you're not trying hard enough!

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Boy is that right. Also just when I think I got it down pat, something weird happens. I do enjoy (mostly) the process. So nice when it works perfect....

Just a question ukesRcool: How many ukes do you plan on making? Chuck and the others are real luthiers who do a lot of production to high end standards and their finishing techniques might not be the right fit for the amateur or the low production facility. Time becomes key as time is money to a luthier trying to make a living. There is a substantial upfront investment to say nothing of learning curves. Their finishes are to die for, but I think for a small production output, shellac works as well at a fraction of the cost. Cost in money that is. Cost in time is something else and that cost is high. But if you have the time and don't have to kick out the ukes, try shellac again. Your first experience might have been bad, but it really does work. It really does. I think a lot of people tend to over think a basically simple process.

Lord I wish there was an inexpensive robot that could do all finishing.

I think for many, finishing is the single most difficult aspect of building, and certainly is if you are looking for glass like mirror finishes. Even as pro's I don't think you'll find many that truthfully say that they like doing them. Quite simply they take time and are an incredible amount of work to get right.

Also I'd like to second Sequioa's comments about using shellac as a finish. You only have to have a look at some of the top Spanish Guitar builders to see what absolutely astonishing results that can be had from using it. Can be brushed on, or with a pad, or a combination of both. You really don't need to make it complicated to get very nice results.

It's very low cost, about as non toxic as you are going to get, and quite enjoyable to apply. I would say it's learning curve is less than learning how to be a good spray applicator.

In 1967, while in the air force as an SP, the airman working in the armory took me inside to show me his carbine stock that he'd finished. It was so smooth and glossy, that I thought it was a thick coat of epoxy. He laughed, and told me it was Tru-oil, and he applied it without a brush. My Fender Jazz Bass didn't have that level of finish when it was brand new in 1964. I'm still thinking about how it dazzled me back then.

A few years later, I started using it on my rifles and shotguns. I've also seen many examples of Tru-oil on various instruments, including my own. It presents an admirable finish, and a close 2nd to French polishing in appearance; for a those who don't have access to spray equipment.

Not having either spray equipment, nor a place to spray things, I have been using Tru-Oil. I have worked out a process that is very simple, not at all time consuming, and yields a very nice shiny smooth surface, yet with a remarkably thin finish. (When scraping off to glue on the bridge the finish seems almost not there at all it is so thin.) I'm going to do a small write-up on my procedure in the near future. For now, here is a picture of the reflection of the banana trees outside the window, and me trying to take a picture of a shiny surface.

That certainly is an attractive finish if you like shiny and I like shiny. Lovely looking instrument. Looking forward to a description of your finishing schedule. Please do write it up and post.

My knock against Tru-Oil and reported here earlier is that I was a Tru-Oil applying slave during my father's dalliance in gunsmithing. It took forever to get a decent finish. Or at least it seemed that way to a 12 year-old. My other reluctance is what the stuff does to the sound of an instrument. Ukes ain't gun-stocks. I have no evidence it inhibits sound, but all that resin...Hell, maybe it enhances the sound. I don't know. Also I've never been able to figure out what exactly the stuff is made out of. As far as I can tell, it a propitiatory preparation of some sort of "resin" in a volatile organic solvent mixture which doesn't really say much. If anybody actually knows, please post.

It's almost certainly an alkyd resin, not far from old fashioned copal or pine resin type varnishes. It's the 'modified oil' bit in the MSDS that suggests it's an alkyd. That, along with heat treated linseed gets you an oil varnish. No doubt there's an added siccative and perhaps a bit of turpentine like solvent. It's not the resin that is considered the problem, it's the oil content. Most violin makers refuse to apply an oil varnish directly on to the wood for fear of it dampening the sound.
I've done Tru oil in very quick time, 3 days from applying the first coat to the final rub out. I was brushing it on and I also have a UV drying cabinet, so I could brush a coat on every 2 hours or so. Rubbing it out so early means that it will shrink back and you'll likely get a softer looking finish, not as glass hard looking. I much prefer that type of finish anyway. You can get the same (or similar) effect with shellac by finishing with the cloth rather than going through all the grits and polishing compounds. It's more like the traditional method of French polishing. The cloth is effectively producing micro lines in the finish which has the effect of scattering the light. It's still a glossy finish, just not as glass like as one would obtain by going through the grits. I think it takes more skill to produce that type of finish. Going through the grits isn't that difficult, it's just more work.
I use shellac for virtually all my finishes but I do apply an oil underneath the shellac. That gives a slightly richer look to the wood grain, which is a little lacking with straight shellac. It's pretty close to an all oil varnish finish in terms of the optics. On the soundboard I don't apply oil, just shellac. That just gives me security. I've no idea if oil on wood is that problematic in terms of tone. I've tried it, a few times. Sounded perfectly fine to my ears.

I have read that Tru-Oil is "a polymerized linseed oil with other natural oils added." It seems to harden rather quickly (in fact, keeping it from hardening in the bottle is a bit of an issue) unlike plain tung or linseed oils. I wonder about your "all that resin" comment. I have found (from scraping bridge areas prior to gluing) that the finish is very very thin, certainly no thicker than a french polish. I always have a seal coat of shellac, and see no deep wood penetration as one might expect of a pure 'oil' finish. The Tru-Oil seems to be very much sitting on the top and is way thinner than any lacquer finish.

I like TruOil for its sound qualities. Not my favorite to apply, no finish is all that fun actually. But try this sometime: build and string up an unfinished uke, listen and remember what it sounds like, then TruOil it and listen again. It truly brings an instrument to life. The difference is quite remarkable. In my use it seems to really harden in the wood and has zero sense of the oil "dampening" the sound.

My preferred type is the spray can. I don't spray it on, but I spray a puddle into a cup, then dampen the application cloth in the cup. The oil in the spray can is much thinner than in the bottle (and it does not harden in the can). I feel like the thinner oil in the can penetrates into the wood better as well. Using TruOil from the bottle is problematic because it starts to thicken pretty soon after opening.