How to fix a crack in the top of an acoustic guitar?

drjones

New member
Hi all.

I scored a Martinez acoustic 12 String on ebay. It was $60 on account of it having a crack in the top of the guitar. I took a punt on it and bought it. It sounds good, but now I need to figure out how to fix the crack. I'm assuming that in time the crack will run. I'm also assuming it would cost a fair to have it repaired, hence the absolute bargain I scored it for. Anyone here know how to repair it? I was thinking of sanding the gloss from the crack, filling the crack with wood glue and putting some weight on it while it dried.


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Re: How to fix a crack in the top of an acoustic guitar?

Cheap fix: don't repair the crack. Just "quarantine" it. Drill all the way through the top on the outermost ends of the crack. This keeps the crack from growing. Then plug those holes (or at least put some poly into them) to keep moisture out of the end grain that you've exposed. It's the same basic approach that is used for keeping windshield cracks from growing without actually bothering to repair them.
 
Re: How to fix a crack in the top of an acoustic guitar?

Thanks, I was considering drilling the end of it as well, but wasn't sure. When you say 'plug' what do you plug it with? and excuse my ignorance but what is poly?

Thanks for the reply too.

Cheers
 
Re: How to fix a crack in the top of an acoustic guitar?

I'd plug them with dowel stock, with the grain running 90 degrees from the sound board grain. If you can get by with toothpick-sized holes, there are your plugs.

By poly, I just meant polyurethane. I.e., if you don't bother to plug the holes you drilled, then at least seal the open grain.
 
Re: How to fix a crack in the top of an acoustic guitar?

Cracks occur because the guitar got to dry or experienced a sudden and radical temperature change that the the wood couldn't cope with. Whatever repair method you decide to go with it's important to re-hydrate the guitar. That usually means you need to get the guitar into an area that has a room humidifier that can supply about 50-70% humidity for at least 2-3 weeks. This will cause the top wood to swell and return to it's original condition and greatly decrease the size of the crack. Once that is accomplished then repair and or refinishing can be done.
 
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Re: How to fix a crack in the top of an acoustic guitar?

If all else fails, play like Tommy Emmanuel. Beat the thing to within an inch of its life. :D
 
Re: How to fix a crack in the top of an acoustic guitar?

Use a very small drill that a tooth pick will fill. Once the hole has been drilled you can dip a tooth pick into wood glue, press it into the hole, let it dry, then trim off the excess then sand it smooth. Then you can brush or spray some lacquer on it to keep it from the weather. Simple easy fix! After you repair this you have to know why it happened in the first place. More then likely the guitar dried out causing the top to sinkl & ultimately cracking the top. Keep the guitar properly hydrated and it should never happen again. Depending on how you store the guitar(on a stand or in the case) when you aren't playing it could change what you need to do. In Winter months if you kep the guitar on a stand in your "music room" you can buy a room humidifier and simply blow water into the air. If you keep your guitar in the case then you will need a case humidifier like a Tamp-it or the planet wave system.
 
Re: How to fix a crack in the top of an acoustic guitar?

Everyone else has offered good suggestions, so I'll just stick to recommending a good humidifier. This is my favorite humidifier. I used to use the PlanetWaves Humidipacks, but when they pulled them 6 months after they put them out (they've since been re-released), I started using the Oasis, and I haven't looked back since.
 
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