High-Build Gloss Finishes for Guitars
Some of the newer products give excellent results, fast. July 3, 2008
Question
When spraying build coats (in this case, once every two hours), is it okay to spray in the same pattern each time? In this case, a guitar. It looks like the finish is going on evenly, but I was wondering if spraying in the same pattern every time will leave me in trouble later.
I spray the sides of headstock, then the front, the neck, etc. Then the back of the body, starting on the right side moving left. After two hours of drying I repeat the process. It probably doesn't matter, but I wanted to make sure.
Forum Responses
(Finishing Forum)
From contributor J:
Are you aware there is a much easier method to close grain these days? Two coats of a two part polyurethane scuff and you're done. You could have the guitar done by lunchtime. Don't get me wrong, your way will work. My old boss still closes grain this way. Takes him about a week to close mahogany, when it takes me two hours. But to answer your question, you should spray from one direction then go back and spray the opposite direction. But overall, you will never notice a difference with the naked eye.
From the original questioner:
Right now, I am using MLC Krystal Clear. I really love the stuff... The finish looks like it's part of the wood instead of "on" the wood like a poly seems to be.
Before spraying, I grain fill using epoxy. Then 8-9 coats of Krystal Clear, level sand (take imperfections out), buff, and it's done. I took some samples to a friend's automotive finishing shop and they sprayed some... Their poly filled the grain but dried too fast, leaving solvent pop. So we moved to MLC Krystal and have been using it ever since. It does take a long time... if you can recommend a better finish, I'd be more than happy to try it out.
From the original questioner:
I forgot to add that I spray a sealer coat of Krystal Clear before filling the grain with epoxy.
From contributor C:
I've been doing musical instruments since the 60's, starting with the old nitros. I presume you're talking a hard body guitar and not a semi-acoustical type. The best method I've used to date is a 2k urethane as an isolation coat and then building with polyester coats afterwards. All the coats are put on in short notice; as soon as one has reached a degree of set but is still tacky, the next coat is applied. In this way all the build coats can be done in a day or less. The next day it can be sanded smooth and a topcoat of 2k urethane or more will finish it off except for final sand and buffing. If you're set up with pro wheel buffers you can just buff the polyester, but it's more difficult to do when using a hand controlled buffer - polyester buffs much harder than urethanes. I also think that contributor J's way works well and that the solvent pop happened by applying the first coat too heavy. If a couple of light coats are first applied and allowed to set up for 15 - 20 minutes before applying the heavy coats, this should not happen. The trouble with auto guys is that they're used to spraying cars that don't have the possibility of air outgassing from the metal they spray. What type of wood are you finishing? Open grain, closed grain?
From contributor H:
According to ML Campbell, the final dry thickness of Krystal should only be 4-5 mils. Sounds like you are putting on way more.
From contributor C:
Good point.
From contributor N:
You're probably asking for trouble spraying Krystal too thick. If you're comfortable spraying that, try 2k. I sprayed a replacement neck a while back with some and it really doesn't look any different than if I sprayed it with lacquer. They have a sealer for it to fill the grain. Sand it back, then start topcoating tacky between coats. I would get it to where you want it, let it sit overnight, sand it one more time, and spray one more coat on it. Then buff. I actually used a satin because I like the feel of it. Then buffed just the headstock out as shiny as I could get it. Although I still like how the old nitros age and wear.
From contributor R:
Ilva makes an excellent high-build urethane and topcoat. IC&S distributes their products. They dry fast, build fast and buff out beautifully just like urethanes in the good ole days.
