Hi All,
I know this problem has been discussed many times, but I still get trouble with it. I thinned my lacquer about 20 %, when it wet it look very good, but it started winkling during the drying time. It was a hot day, 96 F , is temperature also the fact causing this? Thank you.vn
Replies
Hmmm... wrinkling is generally indicative of an unfavorable chemical reaction taking place. What material are you spraying? What, if any, sealer material is it going over?
Regards,
Kevin
Hi,
I shouldn't say winkling, what I meant is orange peel. I thin with lacquer thinner and spray with my HVLP gun on the bare wood. The firstn 2 layers seem OK, but the last one causing that. I wonder that I spray too thick or because the temperature go hight at tha t time. Thanks.vn
Try waiting at least 2 hours between coats with air moving over the surface.
Spray lighter coats, and thin only about 10%.
Don't spray in direct sun.
Well.... spraying at too thick of a viscosity while not putting enough on to let it flow out can cause orange peel. Likewise, if the ambient temperature is higher during your last coat than it was during the first two coats, that too can cause orange peel unless compensated for. In fact those are the two most common causes of orange peel.
I would suggest either adding more thinner and spraying a lighter coat (enough to completely wet the surface, though)... or maintain your current reduction method and add some retarder. The retarder will keep the surface open longer and allow the lacquer to flow out properly. Here again, I would caution spraying just heavy enough a coat to get the surface completely wet but no more. If you're spraying strictly a horizontal surface, it's no big deal. But, the retarder keeping the lacquer open longer can pose a problem on vertical surfaces if you spray on too heavy of a coat - it might want to run or sag otherwise. Personally... I'd go with the first option if you already have enough build from the first two layers. If that's the case, then all you need this last layer of lacquer to do is flow out nicely to give you the finished look you're after. A thin coat of well reduced lacquer will do that for you.
Another way to look at this is to understand that the spray cans of lacquer that are widely available in paint and Home Base type stores virtually never cause orange peel, but they don't build up very fast either. This is because the material in the spray cans is very thin - i.e., there's a lot of solvent in the spray can mixture.
You might also try dropping the atomizing air pressure as low as you can without sacrificing sufficient atomization. In hot conditions, excess atomizing air can cause the lacquer to partially flash before it even hits the surface - leading to insufficient remaining solvents to enable the lacquer to flow out properly... i.e., it will orange peel.
Regards,
Kevin
I agree with Kevin, you're shooting it too dry. I shoot lacquer between 3:1 and 4:1 and use good quality tinner. When I've goofed a little and gotton some orange peel it's always because I was shooting to dry or moving too quickly. I've only spayed lacquer with a conventional gun but the thought occurs to me that if you're using a turbine in a high ambient temp then you may need to go to 3:1 and add retarder. The good news is that, within reason, you can't really over-thin lacquer. Another fix is to shoot straight thinner or nearly so (I do it when I'm cleaning the gun) on the surface just enough to wet it. It will re-melt the surface and let it flow out a little bit more and take care of mild orange peel.John O'Connell - JKO Handcrafted Woodworking
Life is tough. It's tougher if you're stupid - John Wayne
Hi All,
I thinned with lacquer thinner from Home Depot. I kind of confusing here, the more thinner the faster it dry? It was true that I sprayed heavier at the 3rd & 4th coat, also I think the presure was hight . I use a HVLP gun with 3 hP comprssor, my gun is regulated at 10 psi, and I used its max. vn
"within reason, you can't really over-thin lacquer."
ELCOHOLIC,
While you qualified your statement, I have to disagree somewhat. When you thin a lacquer, you reduce its cohesiveness. That impedes its ability to flow out. Granted, it can't flowout if the solvents have already evaporated.
That's one of the reasons why Kevin, and myself on occasion mention using thinners that evaporate slower. These problems (based on how often the question keeps coming up here during the summer) are caused by using the wrong thinner for conditions, as well as some other stuff that effects it all too. These include spray gun PSI, flow rate, fan air mix, application speed, gun distance from work, etc, etc.
Well... I'm gonna come down somewhere in the middle here. Provided one is using the lacquer thinner blend recommended by the lacquer manufactorer, I would agree with Elcholic. But... over-thinned lacquer is difficult to work with because the solids settle out very, very quickly. It requires very frequent agitation to keep the whole mess in solution.
Personally, the only use that I have for over-thinned lacquer is for doing repairs. I would define "over-thinned" as reducing the lacquer 50% or more. For production work I never reduce more than 25%. Most of the time I reduce 15 - 20%.
Regards,
Kevin
"For production work I never reduce more than 25%. Most of the time I reduce 15 - 20%."
Kevin,
Wow. Here I am saying that you shouldn't over-thin lacquer, and you are shooting at 20%. The stuff I use (PPG) has a recommended thinning ratio of 200%, though I typically find 70% gives a good gloss and flowout, closely mimicking a catalyzed urethane like Delstar. I do sometimes thin to ~800% for small stuff (sprayed at 3PSI) when gloss isn't important. Clearly we use very different products.
Jon
Jon
Clearly we use very different products.
LOL yes, clearly we do. I'm shooting Sherwin-Williams topcoats on wood.
That's the problem with general advice IMO. It is so relative to the exact brand and type of finish that readers should be careful to inquire about the specifics before charging off to replicate exactly what they believe the person giving the advice did.
Regards,
Kevin
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