I take on one or two commissioned projects a year for cabinet or furniture work. I struggle to get professional finish results, which is driving me crazy. Bubbles have been my enemy. My finish choices have been General Finishes (Enduro Var or White Poly) or Target (EM6000 or EM8000) water based finishes.

I critiqued my setup from top to bottom this year to weed out potential issues.

I installed new hoses and filters after the compressor in addition to a Whirlwind filter at the base of the guns.

The shop is warmed to 70 – 75 degrees F. with the finish at a similar temperature. Humidity is 50 – 60%. I stir and strain the finish through a medium mesh filter the night before into PPS cups to allow some time for bubbles to settle out.

I generally build with maple, cherry, or walnut. The surfaces are sanded to 220 grit. Dust is removed with a blast of filtered air and/or a microfiber cloth (no tack rag.) I may apply a one pound cut of dewaxed shellac to highlight the grain, which I mix up in house. I allow it to cure for a day or two before the top coats are applied.

With a Devilbiss FLG4 gravity HVLP gun, pressure is set to 18 psi with the trigger pulled. On a Sata knock-off RP gravity gun, I have the pressure set to 28 psi. I aim for 3 mil wet film thickness, sprayed about 8” away with 50% overlap.

I have adjusted air pressure, film thickness, spray distance, room and finish temperature, viscosity, retarder, fan on/off, 1.3 or 1.5 mm tip, etc. A couple minutes after spraying, bubbles are everywhere. I come back 30 minutes later hoping they would settle out, but it just isn’t a quality result. The first coat or two are fine as the wood absorbs, but once the surface is sealed, bubbles are very evident after curing; in a quartering light they are visible and when you run your hand across the surface it is not as smooth as it should be. The spray guns are cleaned after each session with warm water, followed by watered down denatured alcohol.

Target and General Finishes haven’t given me satisfaction, and I have combed through Woodweb and other blogs. I would greatly appreciate any ideas!

Jim

Sounds like you've gone through the gamut. As I recall Target wants 2-3 mil per wet coat. It's pretty light. Not to hard to go overboard. Make sure there is minimal or no airflow over your parts while they dry. Same thing with heat sources. Nothing direct on the parts until they've flashed.

I would stay away from the shellac, but I understand you wanting the glimmer from the shellac vs the pretty dead waterborne finish.

Are you scuffing with their recommended type of sandpaper? Not grit, sometimes they want no stearates in the paper or a certain abrasive medium.

Good luck.

Long time 20+yr GF user here. And full time cabinet finisher/long time woodworker.

Our setup is roughly the same I've got multiple flg-4's I use for stain, shellac(under pigmented GF), pigments and clears. But I use a 2.2 tip in all of them. And I run them at 45-65lbs at the compressor on a 50ft hose with no gauge at the gun. I adjust by feel not lbs of air. And I only have water trap at the compressor.

I've used Zinnser dewaxed many times and a couple of times a 1lb cut from chips I mixed in house under GF w/no issues. And all my GF pigmented work has Zinnser shellac primer under it to keep the grain raise at bay.
Key is 1st coat of GF sealer needs to light. Light sand and off to the races w/1-2 coats of SS and then topcoats. Have used the Endurovar once on some floors with no issues.

One key I've found w/WB is moving plenty of air over them as they dry in the racks. Flashes them off quickly. And no issues ever w/bubbles. I never turn the fans off until all pieces have flashed off. That could something to look into.

Also I would never use micro fiber, too much bite. I use a well broken in cut up cotton t-shirts/rag mostly for the dustiest pigmented/undercoat stuff. I think the current one is running on a few years old. But mainly parts are aired off and good to go.

I use warm water clean up as well. I'll run 2-3 cups through the gun after a session. I would stay away from any solvent unless your doing a thorough cleaning and then I would want to shoot a couple of coats of sealers before any topcoats to clear any debris/solvent that might linger.

I don't think 220 is necessary. Especially on hardwoods like maple, oak or walnut where burnishing can be an issue. I only go to 150.

BTW have you shot some finish on a clean piece of glass? If it's a contamination issue it will show up there.

my2cts
cheers Bart

Thanks Leo and Bart. I have some homework to do with your feedback, starting with shooting on glass, trying a larger fluid tip, and managing air flow.

I have been doing woodworking projects for 40 years. So many of the "fine furniture" folks are leaning toward wax/oil products such as Osmo and Rubio, and they have their place. But an off the gun, smooth as silk finish can really make a statement as well. I started with a Fuji turbine for a kitchen project 10 years ago and it worked fine. As I migrated to a compressor based setup, I was hoping the increased flexibility would give me more consistent results as I dial in the sweet spot. But there are days where it feels like the choke is stuck open and things just don't come together for all the prep work.

Finishing is 1 part chemistry and 3 parts voodoo.

Not an expert on water base finish I do know after spraying cv for over 25 years if a finish is making bubbles in finish you need to restard slow done drying so air will seep out of the wood ,a sealer coat can help it penetrates down in your wood