What Causes white haze in newly sprayed nitrocellulose clear finish?

I just sprayed @ 82% relative humidity, 65 deg F. Would this be the cause?
Chris
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On Sun, 12 Oct 2003 23:20:34 GMT, snipped-for-privacy@telus.net wrote:

Yes, particularly if you laid on a heavy coat.
You can wait and see if the moisture that is trapped in the finish will release over time.
Or, you could load the gun with pure lacquer thinner and spray on a light coat.
It's a judgement call but in most cases, if the hazing is heavy enough to obscure the figure of the wood, I would spray with the thinner.
Lightly.
Regards, Tom Thomas J. Watson-Cabinetmaker Gulph Mills, Pennsylvania http://users.snip.net/~tjwatson
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If It doesn't go away after a fair amount of drying time, say overnight, Just spray it again with a 50/50 mixture make sure you do not lay it on to heavy but be sure that it looks wet when you do.
Good Luck, Georeg
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On Sun, 12 Oct 2003 16:39:31 -0700, "George M. Kazaka"

I wouldn't wait so long. And I wouldn't use a fifty-fifty cut of lacquer/thinner to do the job.
If you wait, you run the risk of the included moisture raising the grain of the wood.
I see no benefit to using a fifty-fifty cut in preference to a spraying of straight thinner.
Regards, Tom Thomas J. Watson-Cabinetmaker Gulph Mills, Pennsylvania http://users.snip.net/~tjwatson
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The longer that you wait, the more "cured" the lacquer will be (more difficult to release the moisture). Use straight thinner; the sooner, the better.
--
Alan Bierbaum

Web Site: http://www.calanb.com
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More than likely if you wait overnight the moisture will come out by itself, I have found it rare that it didn't come out in a few hours, a real bad case would be gone overnight, and actually I would usually just shoot it again without thinning, My 50/50 suggestion was just a cautionary recomendation for a novice. I sprayed lacquer for 28 years in just that type of climate with at times more humidity than 82% You may find that only a small area may have the haze, it takes Nitro Lacquer at least two week too "CURE" Sometimes more in a high humidaty area. I know it costs a lot more but try to get some Acrylic lacquer, or Butrate lacquer they are much better and gives you a harder surface and whole lot leass of problems or color changes. If you spray straight thinner you have to lay on enough to soften up what you already put on and this is going to cause it to have a strong possibility to run.
Let us know what you do and how it turns out, Good Luck, George
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overnight,
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On Sun, 12 Oct 2003 20:10:46 -0700, "George M. Kazaka"
First of all, thank you all for the reply's. I appreciate the help.
The hazing is in three spots which I would call about 1/2 in wide by 4 in long.. They are in corner areas where it is conceivable that the lacquer went on thicker than normal.
I cannot spray again until tomorrow (monday) so I will have to wait. The piece has been sitting for 7 hours now but I am not sure whether the haze is disappearing. There is still visible haze and I will keep and eye on it.
This is not the first coat over the wood however. It has received possibly 5 previous coats before this, some from months ago. I stopped spraying because august - september was just too hot here.
It would seem to me that the moisture will not effect the wood because of the previous coatings.
If the haze is not gone by monday then is spraying another wet coat over top the best way to deal with this? I could always wet sand it out. I have to wet sand it anyway. I am not sure what I would do if I spray another coat on top and the haze is still there.
Chris

To e-mail me, remove all of the sevens from my address.
Chris
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Read this entire thread and wonder why no mention of retarder. In high humidity if you mix a retarder in with your finish it slows the drying time and allows the moisture to excape the finish. Moisture is not at home there it is just trapped because the finnish skins over before it can escape and the skin creates a barrier. Don't try to spray retarder straight unless you can lay the sprayed side flat. It will cut the finish and allow the moisture to escape but will also allow the finish to flow downhill. I used to have a very open shop and alot of problems with blushing.

the
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usually, when you have a milky or white finish, it is moisture in the lines. You did bleed the line before you sprayed right?

sooner,
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On Wed, 15 Oct 2003 13:42:38 GMT, "js"

The air is dry. The finish had just a few spots where the finish was slightly hazed. It sprayed another coat on top at 78% relative humidity and the haze is completely gone now.
Chris

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Chris
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Yes.

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