Guitar Finish Repair - Luthier Tips du Jour Mailbag
In this episode, Robbie O’Brien shows how to repair a cracked finish.
Video Transcription
[on-screen text reads: Luthier Tips du Jour Mailbag]
Mailbag question: I'm having an issue with the finish chipping off at the neck joint. How do I fix this?
Robert O'Brien: Today's Tips du Jour Mailbag question comes to us from Loveland, Colorado. "Robert, I built a guitar using your online course, but I'm having an issue with the finish. It is chipping off at the neck joint. Is there a way to fix this?" Rod in Loveland, Colorado.
First of all, Rod, thank you for getting my online course, and I'm glad you're finding it useful. What you're describing is actually fairly common. You have a lot of things coming together at that neck joint, sides, the bindings, the purflings, the fretboard, the heel block itself, and there's a lot of expansion and contraction going on in that area. And you're asking a lot of any finish to be able to keep up with that kind of movement. There are ways to fix it. Let's go to the bench, and I'll show you.
So Rod, here's the problem on this guitar. There's a little finish crack right along there, and that's due to wood movement. Now, perhaps it's also due to some craftsmanship. If there's any little minute gaps or anything, if you tried to fill it with a pore filler or something before you did your finish work, these kind of things can shrink over time, leave voids in there. And along with the wood movement, then you've got this finish crack coming along there. It's really tough to ask that much of a finish to accompany that wood movement, so we got to fix it.
Refinish with GluBoost Fill n' Finish
Here's what we're going to do. This is a lacquer finish. Ideally, sand everything flush. You'll probably get into the wood a little bit, but get it all back to square one and refinish it. You're looking at several weeks to do that. A quick fix is to use a CA glue to stabilize your lacquer that's wanting to chip off and to fill the void. And you can usually get a pretty decent finish with a CA glue. So that's what we're going to do on this guitar so we can get this guitar back out on the road.
So Rod, I'm going to use the GluBoost family of products to do the repair. It's CA glue that comes in a variety of viscosities, ultra thin up to a little bit thicker, and then, of course, the accelerator. So I'm going to start by putting just a little bit of masking tape right up next to that seam, and that will help me strategically place my CA glue a little bit better rather than trying to get it all over everything. And if I have any drips or something, that will help keep everything clean.
Now, I'm going to take a very small pipette. I've got the UltraThin GluBoost in here. It's like water. And I'm just going to strategically place a drop or two onto that seam. And sometimes, it's just enough to run right up under there. See like that? Runs up under there, fills that void, helps with your discoloration there of the lacquer. It also helps stabilize that lacquer, so it's not going to want to chip off.
Now, I've got a little area there that's still white. It doesn't want to roll up under there and get under that lacquer. So what I'm going to do is just take a little pin and put a little pinhole in there and get that lacquer to go up in there, or get the CA glue to go up in there and help turn it the clear color again rather than that white color. So I'm just taking a little thumbtack here. I'm just going to very gently put a little hole. And see how that lacquer just slipped right up under there? There we go. Now, it's turned it back to the nice shiny color, the glossy color, rather than having that white loose lacquer on there.
Now, that might be enough. However, if you still have a little void or something, you have to fix that levelness, and that's why we come in and use a little thicker viscosity to help level that finish. Right now, I'm just going to hit it with a little bit of accelerator and let it dry. I'll take my tape off, and we'll evaluate whether or not we need to fill any low areas.
Before I remove my tape, I'm going to take a razor blade and just lightly skim the top of that. Try and get it a little bit more level while I have the tape to protect the wood. Now, I'm going to remove the tape.
Level the CA glue
Now, I'm going to come in with a very hard sanding block, I mean this is 600-grit paper, and very lightly hit this area. The reason why I'm using a hard block is because I want to make sure that I level that CA glue. The next thing I'm going to do is hit it with some thousand-grit wet dry paper. I'm going to hit just a little moisture on there. And I'm going to repeat that process now with some 1200-grit. Very lightly.
Buff with swirl remover and polishing compounds
Now, I'm just going to take some car polish type stuff, this is a little heavier cut, and start to buff this finish back up to a gloss. This has a little abrasive in it, so it will scratch. And here we go with the fine swirl remover. Get it back to a high gloss.
So after buffing it here with some swirl remover and some polishing compounds, there's what we have, and I think it turned out fairly good. At least that lacquer won't be chipping off of there anytime soon. Ideally, it's probably better to take it back to bare wood and put another lacquer spray coat on there, but client wanted to get it back on the road, so that's what we did. So Rod in Loveland, Colorado, thank you for your question and happy finishing.
[on-screen text reads: More Luthier Tips and online courses available at www.obrienguitars.com. Private and small group guitar building and finishing instruction available.]
