Nitro clouding problem

[hummingbird]

I have applied 6 coats of Watco rattle can lacquer to my #2 with good results so far. However, this evening I sprayed a coat which immediately turned cloudy in a weird pattern which follows the bracing pattern on the top and bottom. The top is bear claw sitka and the back is padauk. The neck also has some cloudiness. See PICS. WTH I'm freaking out!!

Here are some of the factors...
- I keep the guitar and neck in a very low humidity shop < 30%
- I bring them outside just before I spray, then I spray, let sit for 5 minutes and return to very dry shop. This has not caused a problem so far
- It has been cool 40 - 45 Deg F ish for the last 4 coats but as I said I return the guitar to a warm dry shop shortly after spraying and has not been a problem.
- I do not store the cans outside.
- Yesterday was warmer 55 deg F and I applied 2 thicker coats two hours apart. It was looking great!!
- Just before I sprayed this coat I sanded with new 400 grit sand paper from home depot. I used 320 on the previous coats.
- Today It rained and was still fairly damp and 50 deg F when I sprayed a fairly heavy coat which resulted in the problem.

I'm baffled and really deflated. This guitar was turning out really nice. Help!!

[B. Howard]

What you are seeing is called blushing. It can be caused by moisture, was it more humid the day you sprayed the last coat? that could be the culprit. Using a spray can there is little you can do but if spraying conventionally you can add some retarder to the mix to avoid this. I suspect this problem was made worse by moving the guitar back into your shop so quickly. Your shop RH seems way low to me and this could have caused the surface of the coating to dry quicker than the rest, trapping moisture and vapors in the film. I like to keep my shop at 45% RH, and personally think anything less than 40% will lead to problems at some point. Behlins, Mowhawk and others sell aerosol blush removers that you may be able to use to remove the discoloration. Spraying a coat of retarder will do the same.

[hummingbird]

Thanks Brian

This morning I checked it and if I scrape the cloudy parts with my fingernail it seems to remove some of it. See Pics. What if I wipe it with a paper towel lightly dampened with lacquer thinner?

[hummingbird]

BTW Happy birthday Brian!

[B. Howard]

BTW Happy birthday Brian!

Thanks.

Thinner may be enough to remove it since it is not very deep. Wiping the thinner on however would not be a good idea. You need to re wet the lacquer sufficiently enough to let the moisture work it's way out. Wiping will really mess up the surface and you may need to re-wet with thinner a few times to keep the lacquer wet long enough to work it out. That's why retarder or at least a very slow thinner would be better. You need that slow evap rate to let the moisture work back out.

[tippie53]

There is a product called No Blush and you can get that it most bg A auto parts. I am sure Brian may post. I have also used a spray bottle and use thinner and just fog the body to let the moisture out.
It can also often work out on its own if given time.

[hummingbird]

The surface is soft like it needs to dry more. I tried sanding it and its not dry enough. It just gets gooey and clogs the sandpaper. If I keep it in my dry shop for a few days do you think it will harden more so I can sand it?

[B. Howard]

Sanding back is an option also, but as you noted you will need to let the lacquer cure a spell before you can do that. Most likely will need to wait a week at least before it will sand cleanly. John's idea about a spray bottle is a good one, assuming the thinner doesn't eat the plastic spray bottle itself.