Problems with Orange Peel in On-Site Lacquer Application

Thinning, retarding, and modifying the application technique may help an architectural woodwork finisher reduce this top-coat orange-peel problem. January 27, 2007

Question
I have been doing finishing on doors and trim for the past few years. For the last two houses, I bought a CAPSpray 8100 HVLP sprayer to apply my stains and lacquer. The problem is my second coat of lacquer isn't as smooth as the first. After staining, I spray the first coat on and let dry. I lightly sand and the finish is glass smooth. I then spray the second coat on and I get a little "orange peel" feel to it. I have just started using some lacquer retarder and it helped a lot, but still isn't as smooth as the first coat. I also use a #3 tip like it recommended. Is this normal?

Forum Responses
(Finishing Forum)
From contributor D:
Try reducing the finish a little more with thinner so as not to use too much retarder, and maybe open the fluid tip up so that you are spaying a heavier coat. It sounds like you might not be laying down a wet enough final coat.



From contributor B:
I've had problems with orange peel in pre-cat lacquer. Two things have helped: 1. increasing the air pressure, and 2. thinning the lacquer.

My understanding is that orange peel occurs when the viscosity of the lacquer is too high. Consequently, the lacquer doesn't have a chance to "lay out" before the solvents evaporate.

Because viscosity is affected by temperature, maintaining your spray area at a constant temperature should make for more consistent results. I've also read that, but not tried, heating your finishes to about 100 degrees F produces excellent results.



From the original questioner:

Does thinning the lacquer hurt the durability at all? Can I use straight lacquer thinner or is there something else I should put with it?

But as was said above... It doesn't have a chance to "spread out" on the second coat. The gals at Sherwin Williams said the same thing. I have tried spraying it heavier, lighter, more pressure and less, and still haven't gotten away from it.



From contributor D:
Straight lacquer thinner is what you use, but be sure to use a high quality thinner that is recommended by the lacquer manufacturer. Some thinners are used for cleaning equipment and some are used for reducing lacquer. Thinning the topcoat a little should not hurt the durability. At least in my experience this has not happened.


From contributor T:
I would only add that if you're going to thin more, you want to get a "cool" thinner if possible. Lacquer thinner is a stew of solvents and recipes are not all the same. Some evaporate very quickly (hot) and some more slowly (cool). You can cool a hot solvent by adding a retarder, a flow out additive (basically the same thing) a little butyl cellusolve, or some MAK (not MEK).


From contributor W:
Turn your material down on your gun, and maybe your air. Too much air causes too much overspray and wastes a lot of material.


From contributor J:
Call a Kremlin rep to get a demo on an Airmix system. HVLP is not meant for topcoats, or for that matter any high solids or high vis coating. The only way to break up the coating is to increase the air pressure, which in turn dries out the coating. You lose. The AA units use very little air - the coating is finely atomized and is able to flow out for a smoother finish.


From contributor R:
"HVLP is not meant for topcoats."

Wow - you shivered my timbers with that profound statement. Do you care to elaborate?



From contributor J:
Maybe I was a bit harsh. I just struggled with HVLP for many years. I one day had a demonstration with the Kremlin 1014 and was totally impressed. It was night and day. Part of my problem was my compressor could not put out the cfm required for HVLP. The Kremlin unit only needs about 3 cfm, so I could just hook up and go. My finish is much better and I use less coatings. My cost for parts is maybe $150-$200 a year. I easily save that and much more on electricity and coatings. The 2 grand or so I spent was steep back then, but I would do it again no doubt. I also was in Atlanta for the big wood show a couple of years back wow! - and saw all the big machinery displays with Kremlin guns on them. The sales jockeys tell me that most all these machines that spray topcoats and sealer use these type guns because of better finish and reduced coatings cost.