Problems spraying USL Combined

[Brian Hale]

I'm getting a very rough finish spraying USL (HVLP)

Birch wood stained with a gel finish thats been drying for 3 weeks. I stirred the finish well and filtered it twice with a medium paint filter and sprayed till the surface was "wet".

I get the same rough surface on bare wood so i don't think it's gel stain.

I sprayed shellac last weekend with the same HVLP set up and cleaned the gun like i alwyas do. I've had it for ~20 years.

Any ideas???

Brian :mad:

[Jamie Buxton]

In my experience, the first coat of any water-based finish raises the grain -- a lot. I expect to resand the piece after the first coat. It doesn't take much --- 400-grit on a palm sander, just skimming around the surface. Even hand-sanding does the job. You're just knocking off little nibs.

[Brian Hale]

Thanks Jamie

The surface is more like the orange peel ya get when lacquer dries too fast, smooth peaks and valleys as opposed to the sharp points of raised grain. Is that how WB finishes raise the grain, even thruogh a stain?

Guess i should have described it that way in the first place.....

This is my first time with WB finishes, i've been spraying lacquer for quite awhile.

Brian

[Brian Hale]

I also posted this on the Finishing forum.......

I'm getting a very rough finish spraying USL (HVLP) similar to orange peel you get with lacquer when it dries too fast, smooth peaks and valleys as opposed to the sharp points of raised grain.

Birch wood stained with a gel finish thats been drying for 3 weeks. I stirred the finish well and filtered it twice with a medium paint filter and sprayed till the surface was "wet".

I get the same rough surface on bare wood so i don't think it's gel stain.

I sprayed shellac last weekend with the same HVLP set up and cleaned the gun like i alwyas do. I've had it for ~20 years.

Any ideas???

Brian :mad:
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[Jason Roehl]

What I've found to work very well under WB coatings is a quick coat or two of dewaxed shellac, specifically Zinsser SealCoat. It sprays out real nice, and is very quick to dry. Then the WB finishes won't raise the grain near as much. (SC is also called a "sanding sealer" for that reason).

[John Lucas]

Brian,
Did you dilute the USP at all; if you did, did you use their thinner; did you use a drip cup and test for viscosity? It sounds to me that it either needs, thinning, or a larger nozzle tip size. Are you using a suction cup or a gravity feed. If cup, is the seal good and what pressure are you using. Besto bet is probably to post and get answer from the Target forum. Let us know what you do.

[Brian Hale]

All good questions John! Sounds like we're working from the same check list.

No thinner, straight from the can. I checked viscosity with the drip stick from the gun maker, a tad thick but OK. I also tried a larger nozzle designed for paints but that was worse as i couldn't get good coverage without runs. It's a suction cup with a good seal.

So far the best i've process is full air (5psi/58cfm) and very little finish with slooow motion. Sanding between coats knocks out most of the roughness but i've got plenty of final sanding ahead of me. :(

The Target forum is down......

All is not lost, i'll get a workable finish but maybe thats what i should expect with WB? I normally use NC lacquer and i was close to going that route a few hours ago.

The battle continues!

Brian :)

[Keith Christopher]

Brian,

Be sure and stop by the homestead finishing forums. The live for this stuff! :D

www.homesteadfinishing.com (http://www.homesteadfinishing.com)


Keith

[Jim Becker]

I had a similar problem not long ago...Jeff Wiess's first question was relative to moisture abatement in my air system. He was correct...and that's the reason I did so much filtration on my new "permanent" air system. (The same question was asked in his forum by someone else not long before I had the issue)

[Jim Becker]

Per my comments in the similar thread in the General Woodworking Forum, when I had a similar problem, Jeff Weiss (pres of Target) suggested checking for moisture in the air system first. Outside of that, Orange Peel-like texture may be a sign you're putting on on too thick...and that could be either technique or a mis-adjusted gun.

[Brian Hale]

Jim, My HVLP setup is one of those with a 2 stage turbine so the gun isn't being run from a compressor and moisture shouldn't be a problem. As for being too thick, if i put on less it just looks like overspray but i'll give it a go tomorrow. Perhaps since the turbine gives me warm air thru the gun the finish is partly drying before it reaches the surface?



Kieth, Thanks, i'd forgotten there is a forum over there! BTW, the customer is almost ready for these DVD cabinets!!!! :D A few more weeks and Show Me The Money!

Thanks
Brian:)

[M. A. Espinoza]

I've had better results with laying down a sealer first. Used Zinsser Sealcoat and it really helped the USL lay down better.

My setup is so different (gravity feed HVLP) that I can't comment on your hardware setups.

The shellac sealer did wonderful things for the grain raising issue with water lac. Handles much like solvent now.

2 coats sealer/scuff sand/2 coats USL

[Jim Becker]

Brian, I'm not familiar with the Turbine systems. I'd suggest you contact Jeff at Target to see what his advice is. (And please post it here... ;) )

[Brian Hale]

The second gallon sprays better then the first!!!