Does anyone on the forum have experience spraying lacquer? I was spraying a t&g cypress ceiling last week and ran into an strange problem.
The ceiling is 22 feet long and 25 feet to the peak from the floor. I had scaffold set up with long walkboards so that I could go across the whole ceiling from side to side.
I would spray about six feet side to side and about six feet up and down and then move over and do it again.
After going across the ceiling I would then move the scaffold down and do it again on a lower section and repeat this until the whole ceiling was done.
The problem came on the section overlaps. There would be this non-shiney area where I would overlap on the sections. It was about 3 inches wide. From the floor you couldn’t see it but on the scaffold it stood out.
No matter what I did I couldn’t get rid of these areas. Any ideas and advice?
James
Replies
The only thing I can think of is the over lap is taking a little longer to dry, If that's the problem it should even out in short order, maybe a few days or so.
Sounds like you did every thing right.
I just re-read your post and I see you said "Non-shiny areas" I would expect the over laps to be more shiny and my above listed thoughts would make more sence.
Did you hold your gun at the same distance & angle from your start & finish of each stroke? If you arch your sweeping motion of the gun the outer edges of your stroke may be thinner leaving the finish thinner or more misted hence the dullness.
If your finish is still wet after your finished moving the scaffolding everything should blend in but being lacquer, it probably is pretty dry by the time you move & re-set up & start spraying again, then add in arching motion in your sweeping motion of the gun, you will get dry looking edges. The area you are spraying is large & can be a little tricky.
Hope this all makes sense & helps
Best of luck
Paul
No one should regard themselve as "God's gift to man." But rather a mere man whos gifts are from God.
Was it milky in the paint? What I mean is was the texture of the surface or in the paint?
You might want to take this over to Fine Wood Working. They have a section on finishes.
I'm not sure but I think laquer can get water in it.
If it's nitro, you can "flash" coat it with a 50/50 thinner/lacquer mix that will even out any laps. You're gettiing a "feather" overspray of dried material. It'll usually feel rougher than the surrounding area. When you "flash" only spray with the long length of the boards.
If it's WB, you may have to mask the previously sprayed area to avoid laps. Or use satin instead of gloss.
If it can't be seen from the floor why are you trying to "fix" it?
Beer was created so carpenters wouldn't rule the world.
It's overspray. Not sure what type of lacquer or what spray setup you're using but when you are spraying lacquer you need to keep a wet edge. the result if you don't is the flat look you describe.
The time it takes you to move your scaffolding does not allow you to keep a continuous wet edge.
I think two different people hit on my primary thoughts, but both have to do with not keeping a wet edge. One is gun technique, and the tendency to tilt the gun or change something about your delivery at the end of a run, the other, and probably most likely, is that the scaffolding moving, while it only takes a few minutes, isnt letting you maintain the wet edge no matter what your technique.
Spraying another coat can cure it, but you need to make sure that the above 2 things arent going to play into the mix. Thinning it can help, and I would strongly recommend retarder thinner which is still a lacquer thinner (I'm assuming you're using solvent lacquer) but it flashes off much slower. It is usually used to avoid blush in humid conditions but I think you might find it useful here as well. Any paint store likely stocks it.
If its at all possible, set yourself up so you have no delays for moving things. Thats a pretty tall order for a good sized room, but I'd think long and hard walking into it about how to do it all even and fast just so as to avoid what you're describing.
Edit: I just read your location. I lived in Montgomery for years. I almost wonder with the weather the way it usually is if you aren't actually getting a very faint amount of blush. I know there's (or was) a Sherwin on the northish side of Prattville that ought to have retarder thinner. The other Sherwin I recall was out in East Mgy by the mall in the strips that surround it.
Real trucks dont have sparkplugs
Edited 5/28/2007 10:57 pm by RW
Don't know about lacquer on wood, but in the old days when lacquer was the primo finish on custom cars, we just to wet sand the lacquer between coats and on the final coat. On the final coat, we would use something like wet or dry 2000 sandpaper and then finish off with buffing and polishing. Very labor intensive. Multiple coats, sanded in between gave beautiful depth to the paint job, however. Don't imagine that all of that labor was include din the contract, or how well it would work sanding overhead.
I think everybody touched on what I thought the problem was. I held the gun correctly but since I could not keep a wet leading edge the overlap areas caught a little overspray.
I tried to make it where I could go all the way across but it was to high and difficult to do that. Like Idahodon said, I can't and the builder could not see it from the floor. He thought the ceiling looked great. It just bothered me and I wondered if next time what I could do about it.
I have two HVLP spray units and I thin the lacquer 50/50. We were spraying satin and maybe that is why it could not be seen from the floor.
And yes, we had to sand between coats with a 200 grit paper. It took 3 hours just to sand this ceiling. It took 4 gallons of lacquer for one coat. We sprayed the porch ceilings with polyurethane and of course you don't have this problem because it dries much slower.
Guys, thanks for you input.
It just bothered me and I wondered if next time what I could do about it.
Sorry to sound like I was busting your chops over fixing something that's not broken. Like you, I always try better methods for the time it will show.
As soon as you said satin it hit me that you also might be suffering from a little uneven deglosser. The stuf in satin that makes it satin seems to settle out fairly quickly so it could make the transitions more noticeable. If you stick with gloss except for the final coat that won't be a problem and saves the hassle of stirring since gloss lacquer has nothing to settle out.
I'm not a big fan of sanding lacquer inbetween coats other than a light skif to remove bugs and dog hair and the like if needed. The great thing about lacquer is the number of coats that can be applied with very little prep inbetween.
Take this for what it's worth, but spraying unthinned lacquer is hard to beat. Right out of the can almost everything I'll spray is unthinned. On the final coat I may spray some straight lacquer thinner to blend in some overlaps, but that's it. Some of the overlap marking you see might be partially to blame on the very thin coats you applied.
As I type this there is a 3'x5' coffee table in front of me that has had probably a half dozen coats of gloss nitro lacquer with a single satin coat, with many overlapping coats and no sanding inbetween. I sprayed it outside on the lawn with a slight wind blowing and there are more than a few bugs if you look real close, but no overlap marks even though there should be.
Best of luck and if you find out what was causing the problems let us know!
Beer was created so carpenters wouldn't rule the world.
What he said above this post...when you sweep the gun and trigger OFF on the coulda be lap, you are dry. Overspray that is dry will eventually burn in, but you'll always see it if you know what to look for.
I don't know what Lac you are using or the viscosity/humidity factors..it could just be blush, but I have seen a weird reaction on Cypress, that resembles blush, but actually is the tannins fighting with the Nitro Cell in the lac, When lac flashes off the the vehicle (thinner) it evaps..and COOLS the wood, which will attract and contain water vapor..which in turn pulls out the tannins or "grease" in Cypress
You have the combination of both bads I bet.
Parolee # 40835
Several posters had it right, I think. What you describe sounds like no wet edge where you have started a new section next to one that has already flashed off. If the problem were blushing, it would be all over or would appear randomly, but not just at section overlaps.
You can re-melt those areas together by spraying over them with a straight, hot thinner - butyl acetate works well, some guys like to use MEK for that purpose. Acetone is a powerful solvent for lacquer, but it dries so fast it usually does not allow enough time for flow-out. Ordinary lacquer thinners contain hydrocarbon diluents to reduce cost and so are too weak for re-melting.