I was quite surprised to read in the article “Spray-Gun Choices” in FWW #194, that the author reported very slight orange peel when spraying water-based finished with Apollo and Turbinaire’s 3 & 4-stage turbines. I’ve been spraying “off the gun” quality finishes using my Fuji Q4 Pro, spraying Target’s water-based shellac, lacquer and polyurethane. I’ve found through using my system that the 1.0mm aircap set gives me great atomization.
I’ve sent an e-mail to FWW’s staff, asking the author to provide more info on what aircap size he was using with the turbines he used. I suspect he may have been using one too coarse for shooting waterborne finishes with an HVLP turbine system. His bio gave me the impression he was very experienced, so I’m wondering what’s up.
I’d like to hear of what others have been experiencing, as I feel Kohanek’s article is giving HVLP turbines an undeserved bum rap.
Comments?
Marty in Ottawa, ON
Replies
I've spent a week in a class taught by Mitch. He IS very experienced - and a great instructor. But his opinion is his opinion. Your experience applies to you and I would stick with your procedure.
Frosty
"I sometimes think we consider the good fortune of the early bird and overlook the bad fortune of the early worm." FDR - 1922
Amother issue is our varying definitions for an "off the gun" finish. We have no way to know that your perfect is the same as his. I use a Q4 also, and have used it for several years. I cannot get the quality off the gun with water based finish that I can with solvent base product.
I suspect his very slight orange peel is revealed only in oblique lighting and careful investigation.
I have to say that I am in the market to get a conversion gun set up because the turbine set up causes me too many issues.
Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Mike,
Check this site out for spray guns. My only affiliation is that of a satisfied customer.
http://www.spraygunworld.com/
They even have a special woodworking section. It's a very comprehensive site with a ton of info.
I have a pretty inexpensive Wagner HVLP unit (I got it because it was a "best buy" rated unit in some article several years ago when I bought it) that I got expressly for waterbased finishes on kitchen cabs. I just used the nozzle that came with the gun and have never had any problems with the finish.
Mike Hennessy
Pittsburgh, PA
I have the Apollo 4 stage turbine with their Atomizer gun. My first/only experience was with a high quality latex paint from Dunn Edwards. It took about 4 coats and much sanding before I got a finish worth keeping.
Tried a 1.3 and 2.0 tip and used Flotrol per manufacturers guidelines. Also thinned with water 10-20%. It just didn't seem that the atomization was fine enough, although it was even and consistent. The end result was orange peel. Also, the sheen was dulled, maybe from the flotrol. It did look much better after it dried. Not the quality I'd expect from spraying, but better than brush or roller.
Next time I'll try lacquer as its supposed to be more user-friendly, but it would be nice to get a good result with latex.
If anyone has suggestions I really appreciate it. I'm committed to learning the skill but am getting really, really tired of sanding.
Dave
My understanding is that latex is always a problem (I've been afraid to even try it). The manual for my Fuji Q4, which is advertised as being usable with latex, says flat out: "Most latex paints do not spray well or flow out nicely..."
The problem is that you can't thin it enough. If you thin it so much that it flows well, you compromise its film-forming ability.
-Steve
Latex paints as formulated these days are so low in VOC content that they flow very poorly no matter how they are applied and they are difficult to atomize well. Turbine HVLP's compound the problem because the air stream is warm, which tends to flash off some of the diluents before the stuff hits the work piece.To get good atomization you need lower viscosity, but if you add too much water you can upset the pH value needed for good film formation. I have gotten better results reducing with Floetrol and 10% water and then further reducing with a 10:1 ratio of isopropanol and household ammonia. The alcohol cuts viscosity faster than water does and the ammonia maintains a high pH. Also, the isopropanol flashes off rapidly - much of it in the air, probably - so there is less tendency to sag than with water reduction. You'll have to experiment to find the limits before you spray a real project. Let it dry thoroughly and check to be sure that the final result will be satisfactory with the particular paint you are using.Now, if only I could keep little bugs from finding the wet film irresistable...
BruceT
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