I use retarder in my Nitro when humidity gets over 50%. Sometimes that is not enough and blush still happens. I keep a small touchup gun with retarder in it. After coat flashes, and blush occurs, I lightly spray it with retarder. Lightly! Blush goes away. Wait till that flashes off, then next coat. I also agree with techniques mentioned above to remove cracks. The finish on this guitar appears to be quite thick. Just me?

Some time ago, a friend asked me to restore his Gibson 200 (IIRC). Heavily crazed. He wanted it gone. Never wants to sell it. So I used this technique. I wanted to retain some of the "patina". But it almost all melted away. Has an interesting "aged" look, but no cracks easily visible.

A quick FYI, the only thickness gauge that works on wood that I know of is the Defelkso Positector 200. It is quite expensive at around $2k. Other gauges work great on other substrates like metal but will not give you accurate measurements on a guitar finish.

A quick FYI, the only thickness gauge that works on wood that I know of is the Defelkso Positector 200. It is quite expensive at around $2k. Other gauges work great on other substrates like metal but will not give you accurate measurements on a guitar finish.

You’re right, it is thick. It’s about 0.012". The whole time I kept thinking I was gonna burn through, but when I was finished,.

A quick FYI, the only thickness gauge that works on wood that I know of is the Defelkso Positector 200. It is quite expensive at around $2k. Other gauges work great on other substrates like metal but will not give you accurate measurements on a guitar finish.

I think you meant sand through. But then again, that's the magic of Nitro. Spray area with an air brush...light sand, buff. I believe one of the largest producers (Martin) still uses nitro. You don't want to get it thick. Nitro gets a bad rap amongst small shop builders due to its flammability. Cost of air supply, explosion proof fan (Jenny, Summit Racing), and so on. These are not to be sniffed at. But they are a one time cost. And once you have invested, life gets easier. WAY easier than dealing with waterborne. Way cheaper than UV. And, most important of all: Repairable. Even yours can be repaired.

EM-Tech 6000 is an exception in the waterborne space. It easy to apply (spray), builds well, water clear, non-toxic (but still mask), non-flammable. Can be tinted. Biggest drawback is the blue cast. And its repairable.

Tom—

You will see many posts from Alan Carruth here on the OLF about there being no perfect finish. I agree with that view. Every option has its own set of upsides and downsides. It sounds like you have already read things I have written here about my experiments with UV cure finishes. You should also look for posts by Brad Combs and Brian Howard. They know a lot more than I do about the UV cure finishes. Weighing the goods and bads, I’ve decided that UV curing is the right way for me to go. Many folks will disagree with that choice, but that’s going to be true no matter what you choose. If you go with UV cure, you might want to watch eBay for used curing lights. I have gotten great deals that way. Another option is catalyzed finishes. Either UV cure or catalyzed gives the best protection. But they are more difficult to repair. And paying attention to personal safety is very important, no matter what you apply. Like I said, there is no perfect finish. Good luck with your decisions.

And I agree that your first guitar turned out great! Yes, you had finish problems, but the woodworking looks well done. It’s a fine start. Congrats on that. My first guitar looks like a 3rd grader built it, compared to yours.

I have a Magic Probe. It reads to 1 mil. In the range of guitar top thicknesses, I subtract 3 mils from my readings to match my caliper measure. If you get one, you will have to do your own calibration for your unit. I haven’t used it to measure finish thickness, but I suppose it could be done. My top thicknesses vary by 2 to 3 mils over a small area, so looking for a finish 3 mils thick would be problematic.

Op said he did not want to wait 6 weeks for repairs to nitro. I’m not going to deep dive this. Nobody I know would do that. There are ways to get things done if u know what u are doing.

Another way to shorten wait time is to make sure surface prep is as good as it can get. Nuff said.

I posted here asking how long to let nitro cure. The conclusion was 4-6 weeks. Perhaps my logic is flawed, but if I sand through lacquer when sanding the final coat, I would assume I would need to wait another 4 to 6 weeks after re-spraying until I can sand again and buff. Is that wrong?

It was quite a challenge for me to sit there, staring at my first built guitar for six weeks before sanding and buffing, all the while being unable to play it. I was scared if I sanded through I would have to repeat the entire waiting process.

Perhaps I don’t understand the process properly?

Tom—

In case you feel you would benefit from some guitar-specific finishing instruction, let me recommend a handful of finishing video courses by Jeff Jewitt, access to which is sold on Robbie O’Brien’s Luthier Academy website. That website has lots of good instruction (for a reasonable fee), but for finishing especially, I think the Jeff Jewitt videos are excellent. There are at least four courses I can recommend: spraying nitro, spraying catalyzed urethane, spraying sunbursts, and sanding/buffing. If you want to go the UV cure route, the catalyzed urethane and sanding/buffing courses are the most relevant, and I would recommend looking up a blog post by Brian Howard about how to work with UV cure finishes, and meshing that info with what Jeff Jewitt teaches. Between Brian Howard, Jeff Jewitt, and some of the info here on the OLF, you can get a good start for your own experiments. Good luck.