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Laid down a couple of coats of nitro today and it all blushed. Added some retarder which helped but still blushed.

Question - if it dries white do I need to strip finish or will additional coats bite in and make it ok??

Thanks Todd, as you predicted, it got a little better by itself once it dried thorougly. I scuffed it with 400 and put another 3 coats on (as the humidity went down as the sun came out) and all is well.

sorry for the obvious question, but across continents things can be lost in the translation a bit.

so 2 x stupid question

what is NITRO?
what is NITRO BLUSH?

cheers
matt from New Zealand

Nitro is nitrocellulose lacquer.

Blushing is what happens when a coat of lacquer traps moisture (usually from the air) underneath it; you get a translucent white rather than a clear finish. Usually it happens if you spray during relatively high humidity, and it gets worse as you try to spray thicker coats.

Usually, the moisture will escape as the lacquer cures, but if you get too much, it will permantly have a white blush. For me, the easiest remedy has always been to stop spraying as soon as I see the blush, and if it doesn't go away on it's own, sand down until it's gone.

I spray nitro outside in all kinds of weather. Up here you don't have much choise if you don't have a spray booth, we sometimes have 4 seasons all in one day! I try to avoid the really humid days because of blushing problems and the coldest days because of orange peel problems, but other than that, I find nitro to be very forgiving. If I get blushing that does not go away when it cures, I usually just spray straight laquer thinner over it, and it disappears.

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Rian Gitar og Mandolin

One tip that I was given and have found to work is to rub the blushed area with a soft cloth. The heat generated will work. I had some blush on my most recent build and this worked on most of it. The remaining spots I just shot another coat of nitro on with a tad bit of retarder in it.