View Full Version : HVLP sprayer, advice rquested
04-18-2008, 11:01 AM
i'm absolutely new to the world of spraying on a finish. after a dozen boats, i think i'm ready to seek a more professional look, besides hopefully cutting down on the time spent on this dreaded task.
what do i need? i will be painting on average one to two small open boats under 18' a year, using primarily system 3's water borne paint.
budget is under $300.00
pointers on how to avoid mistakes with this sort of equipment is also greatly appreciated!
04-18-2008, 11:48 AM
If you already own a compressor, then I'd look into compressor-driven HVLP conversion guns. If not, then one of the freestanding HVLP turbine units might work. The turbines will be more expensive, and without refreshing my memory, I'm thinking $300 might be at the bottom end (or below) what might be an acceptable unit.
I spray a water base lacquer (Sherwin Williams Kem-Aqua) with a conversion gun. Tried it with both cheap and expensive turbine units, and the result wasn't as good. Water base products are thicker than typical lacquers (the molecules are actually larger, and the solvent is thickened with additives, IIRC) The cheap turbine wouldn't push the thicker (higher viscosity) material at all. The more expensive one didn't atomize the material correctly. Whatever units you look at, make sure you can tell them the viscosity of material you'll be spraying (available from the product literature, or the MSDS), and make sure they'll warrant the suitability of what they're selling you.
You can also ask the tech folks at System3 what spray equipment they can recommend.
"No one gossips about other peoples secret virtues" -- Bertrand Russell
04-18-2008, 12:37 PM
Check CFM on your compressor and match the sprayer to it.
Some need LOTS of air volume.
I spray urethane and enamel paint through a couple of regular old Devilbiss guns and turn the pressure down to about 40 to minimise overspray.
Go easy on the thinners.
04-18-2008, 12:56 PM
Good luck, I am using a GEO gun and bandit presser pot.
A little pricey tips are $200 each. Here is a good place to start http://www.homesteadfinishing.com They are helpful if you call and ask questions.
04-18-2008, 03:25 PM
For boats that size, you really won't find much benefit to a spray rig of any type, save for laying on base coats which tend to leave troublesome brush strokes that have to be sanded out. Similarly, I'd recommend you forget the water based paint. It is a poor substitute for oil based paint, no matter how much you pay for it. If you want "professional results," use the paint "professionals" prefer. The much touted "environmental benefits" are pure bull****. The "volatile" gas that evaporates from the paint on an eighteen foot boat is probably equal to the amount of methane in a healty popcorn fart.
Despite OSHA and other regulations now favoring HVLP rigs, for the purposes intended here, I'd expect the "weekend warrior" to do a lot better with a standard aspirated spray gun. Properly prepared material in a properly adjusted gun shouldn't produce problematic overspray. In an industrial application, the HVLP will be more economical of material consumption, owing to the thicker application rate with less overspray, but for our purposes, it really isn't a measurable advantage.
After filling and sanding to perfect smoothness, SPRAY a good quality alkyd base coat (Interlux, Zspar or Kirby's) thickly enough to eliminate all "print through" and provide a solid coloring throughout. ("Thickly" means building up multiple coats, not just "heavy spray!") Sand it properly and tack well. Then apply a good alkyd finish coat with a brush. Don't attempt to lay it on too thickly. Three thinner coats are much better than one thick one full of brush strokes and curtains. If you aren't good with a real brush, then use a foam one. Thin your paint properly with thinner and a bit of Penetrol. (Consistency should be about the same as "half and half." If you get past "whipping cream" consistency, you're going to have problems. Same if you get down to the "skim milk" point.) You will get much better gloss application and finish with a brush and properly conditioned alkyd paint than you will with a spray rig. (More paint on the surface, for one thing.) It takes a lot more skill and practice to spray a good gloss coat than it does to brush one on. If you had to finish a fifty footer, spraying trumps brushing, obviously, but for a little boat, spraying finish coats isn't worth the trouble. It isn't like you are working in a production shop where time is money. Take your time and save your money.
And, thank God nobody's suggested that idiotic "roll and tip" crap as yet!
04-19-2008, 08:35 AM
You may find this information on a HVLP spray unit helpful. Looks like a reasonably priced unit under $300.
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