Kobalt HVLP Spray Gun Use With High Gloss Latex Possible

[Tim Vinyard]

Anyone with experience getting moderate viscosity latex like Valspar Ultra high gloss to properly shoot thru the Kobalt HVLP with default 1.4 or 1.5mm nozzle and retain high gloss result? Next nearest larger nozzle is 4mm - too big for latex. No 2mm or 2.2mm available for this unit. Shooting interior doors. I can get it to atomize and volumize properly, good coverage, but lose high gloss finish. I suspect the latex thinned enough with Floetrol (or water, tried both to see) to get it to move thru the nozzle both cause a finish separation, so the final result looks like satin. I am thinning progressively until it moves thru the nozzle, no more than that. If I go many thin coats to prevent runs, get satin finish look. Moderate or heavier coat causes runs. Perhaps I have to face I cannot shoot high gloss latex with this basic model and have to upgrade. I don't want to use oil for this job. Any suggestions to make this unit work for this job?

[Jack Clark]

I can get it to atomize and volumize properly, good coverage, but lose high gloss finish. I suspect the latex thinned enough with Floetrol (or water, tried both to see) to get it to move thru the nozzle both cause a finish separation, so the final result looks like satin...Any suggestions to make this unit work for this job?

Tim,

I've had good experiences with a thinning product called Benjamin Moore Paint Extender. It doesn't seem to affect the sheen nearly as much as Floetrol (if at all). Comes in quart bottles, and a little bit goes a long way. It's not just for Ben Moore paints either, as I have used it with three other brands of thick waterbased "latex" paints. Your local Ben Moore dealer should be able to get it for you. Not too pricey either.

http://www.benjaminmoore.com/en-us/f...r#advs=0&tab=3

[Jason Roehl]

This is why I prefer pressure pot setups for HVLP spraying. You can force the fluid through the nozzle with a higher fluid pressure in the pot, but dial back the atomizing air to get a larger droplet size. Acrylic paints are made with coalescing agents that allow it to do some self-leveling within the short open time. Over-atomization and too-thin coats speed the drying process, not allowing the self-leveling to occur. Whatever the intended sheen of the paint, a flatter, smoother surface will be shinier. Also, I've found that many of the higher-priced enamels intended to give the hard, quality finish and feel of factory-produced pieces have a very narrow sweet spot between too thick and too thin of a wet film.

[Tim Vinyard]

Thanks Jack, I'll give it a try. If all else fails after this product attempt I'll either resign myself to re-priming and doing oil and live with oil application, or brushing latex with floetrol and live with what is left of brush marks.

[Tim Vinyard]

Good advice Jason, thanks. Your explanation is exactly what I am experiencing, as I have been struggling between too thin and too thick. If Jack's product recommendation doesn't solve it with this paint and sprayer to allow for a widening of the sweet spot to achieve the result, my plan must change.

[Jack Clark]

Yeah, I agree, Jason's explanation is excellent.

Thanks Jason.

[Frederick Rowe]

I suspect the latex thinned enough with Floetrol (or water, tried both to see) to get it to move thru the nozzle both cause a finish separation, so the final result looks like satin.

Floetrol doesn't thin the paint, it is a conditioner which improves leveling properties to eliminate brush drag marks. Can be used in spraying applications much like an extender allowing for a broader sweet spot in atomization and how the sprayed materiel lays out. I've only used it a few times, but it did not change sheen of latex paint or "thin" it as water would.

I wonder if the loss of sheen is the result of over atomization and insufficient time to level. I would avoid thinning with water. Usually sprayed latex gets best results from pressurized systems that can push the material out un-thinned. Latex paint may not be a good candidate for your spraying setup.

[Tim Vinyard]

Hey Frederick,
Great thoughts. I did make sure I also sprayed with straight latex, no dilution, with maximum tolerated fluid levels and minimum necessary air mix levels to avoid over atomization, but just enough air mix so no spatter. Also tried Ben Moore paint extender as Jack suggested, and tried it with and without water. I caught a BM rep in the store and he suggested I may need a higher quality sprayer but give the Advance latex a shot (latex with alkyd component for those that don't know), and if it won't spray and settle with even gloss the problem is the perimeter extent of my spray pattern atomizing different from the core spray. He also said if that is what I find, if I don't want to change sprayers or use oil, the Advance product gets a near spray result applied on horizontal surface, brush on then very lightly back roll with Wood-Koter mohair blend 6 1/2" X 1/4" mini roller, let settle and dry 16 hours, lightly dry sand with 320 grit, apply second coat. While the Advance sprayed far better than Valspar Ultra, it still was not uniformed gloss with streaks of less gloss, so I did the brush/roll. The result is very close to sprayed oil. While pricey paint, it is all I will now use in high visibility vertical surfaces for high gloss or gloss where latex must be used.

[Frederick Rowe]

Sounds like you've found a good solution. If you are still interested in what can be achieved with your spray gun (high gloss white coating suitable for trim, cabinets, etc . . .), I would suggest looking at Target Coatings line of waterborne finishes. Their entire line of products can all be sprayed with your gun, are optimized for spray application, and being waterborne - are easily applied in a home shop without use of solvents for thinning or cleaning.

Look through their finishing forum, owner Jeff Weiss answers many questions directly, and as here in SMC, members are very supportive of beginners. From my experience, many woodworkers choose latex paint because it is familiar, readily available, and easy to clean up. All of these finishing requirements can be met by a quality waterborne finish (be it Target Coatings or other quality products such as General Finishes WB line) and are optimized for spray application.

Waterborne finishes should not be viewed as a replacement of traditional finishes, but rather as an excellent alternative often better suited to home shop spray application environments.

http://www.targetcoatings.com/

http://www.generalfinishes.com/

[Tim Vinyard]

Frederick,
Good to know. Thanks. Will have to try out other products for future applications. Targetcoatings forum looks great too.
Tim