The Back
This article is part three in an ongoing series about repairing a severely damaged vintage Gibson LG-2. Please read parts one and two before reading this part, so you can appreciate how we got here.
As you know, we left off last time needing to buy some materials and think for a while about how to continue to re-glue the X-brace. This time, we are going to focus on the 7 back cracks. While I was still waiting for some materials to arrive, I went to work on figuring out how to close the cracks as much as possible before I even considered applying glue to them.
Guitar cracks as large as these are usually caused by the wood drying out so much that the fibers shrink away from all the fibers around them, thus pulling itself apart along the grain lines. The best thing to do for this is to put a damp sponge in the guitar and cover all the holes. I learned this trick from a video Bob Taylor produced describing the way he used a guitar humidifier called a “Damp-it” to get the cracks on some of his guitars to close to the point of being unnoticeable. Here’s a link to the video:
Damp Its are available here:
A Damp-It is basically a long thin section of sponge inserted into a section of green latex hose that clips on to a piece of plastic that covers the sound hole so the moisture stays inside the guitar where it belongs. Since I had no Damp-Its at my disposal, I improvised. One problem with trying to put a sponge inside your guitar is that you probably should’t put a sponge directly on the bare wood inside the guitar. I chose to simply put the damp, NOT soaking wet, sponge on a lid that came off of a jar of pickles, I think, that would fit inside the sound hole:
Makeshift Humidifier
One thing that stuck with me from the Bob Taylor video was this: “You don’t need more water, you need more Damp-Its!” In other words, if you think the cracks aren’t closing fast enough, resist the temptation to soak the sponge and leave the sponge super damp. Instead, use more sponges that are just damp.
Here is what the “sponge assembly” looks like inside the guitar:
Makeshift Humidifier Installed
Now we need to close all the holes in the guitar, so we can keep the moisture inside. The best impromptu sound hole cover that I know of is the D’Addario cardboard string package: with some low tack tape to secure it. One thing about using tape on Nitrocellulose lacquer: before using tape, even low-tack painter’s tape, stick it to your shirt and peel it off a few times, to take some the glue off the surface of the tape. Like this:
Making The Tape Less Sticky
The glue on most masking tape tends to react badly with lacquers, and there’s nothing worse than leaving tape on something only to find that you need to do finish repairs when you remove the tape.
Also, when removing the tape, peel it off at an angle while rubbing the back of the tape, to get it to release easily while minimizing the propensity to pull the lacquer off while you are removing the tape.
So back to the larger problem at hand: I used the cardboard string pack to cover the sound hole, with some “prepared” tape holding it in place, like this:
Covering the Soundhole
Securing the Perimiter
Then I put a strip of tape over the bridge pin holes and the securing screw holes on the bridge, so no moisture could escape from those holes. Then I put a small piece of tape over the end pin hole. With it all sealed up, I left it for 24 hours. When I returned the next day, I found the sponge to be bone dry. That was a good sign, because that meant that the top and back were soaking up the moisture. I did the same thing again, except this time, I used two sponges. And again, I left the guitar over night. From the Bob Taylor video, I knew that lots of patience was needed in this process, as it can take up to two weeks for a crack to close.
I continued to do this for two weeks…and a little beyond. At that point, it seemed like the guitar had soaked up all the moisture it was going to, and the cracks were as closed as they were ever going to get.
I knew I was going to need lots of cleats to keep these cracks even while I glued them together. I could opt to use the amazon links provided in a previous article to acquire some mahogany and make cleats out of that, but I was trying to be extra cost-effective this time out. And as I said before, I was not really concerned with a “restoration” job, but rather, a competent repair job that got this guitar to playing condition as soon as possible.
I got my cleating material from an unlikely place: empty cigar boxes. I went to a local smoke shop in my area, and they sold me some nice boxes for next to nothing. Here’s one:
Cleating Material?
Here’s what it looks like when you open it up:
Notice The Edges
Notice there is a “lip” on the lower box? That is where we are getting the material. If you simply pull those pieces of wood along the edges out, you will find some decently sized strips of Spanish cedar:
Perfect Cleat Stock
The good thing about Spanish cedar is that it looks like light mahogany, but smells better! I took it to the band saw and first cut some strips:
First Cut
And then cut those strips in half:
Second Cut
Now cleats are often a “signature” item for guitar repairmen and luthiers. The way you shape your cleat can often become like a “calling card” for future examiners of the instrument. I tend to shape mine like beveled diamonds, so I first drew the diamond shape on the rough cut strips, like so:
Diamonds!
…and cut and filed them into shape. Then I put some bevels on the tops, so that they would look decent for anyone that cared to peek inside the guitar. The finished product looks like this:
The Finished Cleat
Now, I just had to apply some glue to the under side of the cleat and place it on the crack, with the grain of the cleat running perpendicular to the crack.
Here’s the cleat with glue on it:
Glue Is Applied With A Toothpick
And here it is in the guitar:
Cleat Pressed Into Position
Which brings us to the question: how am I going to apply pressure to the cleat while the glue is drying? I have a secret weapon! Instead of using some kind of bizarre clamping system, I used some rare earth magnets. You can get them here:
These magnets are extremely strong and when you use them, you have to be extremely careful that you don’t accidentally let the magnet go flying and do even more serious damage to the guitar you are working on! A sure grip is essential! Here is the inside view of the clamping assembly:
Magnet Clamp
And here is what it looks like from the back:
Opposing Magnet Has Leather Under It
…and when it is in place:
Finished. Moved Slightly.
Now for the tedious part. I want to space cleats along the length of the crack, at intervals of one cleat every 2 to 3 inches. Based on that assessment, I will need to make 16 cleats for this guitar. AND make sure they are not going to be in the way of the braces that need to be put on later. Also, it is really hard to feel where you are accurately while you’re elbow-deep in a guitar, so it can take a while to get them placed in the right places, especially near the tail block.
There are occasions where a guitar like this that has gone through a significant period of time with no braces, where I need to squeeze the body together to get the crack to be invisible while I’m installing a cleat. Here’s what that looks like:
Sometimes Squeezing Is Necessary
So stay tuned, constant reader! I’m going to go keep making cleats and glue them in with the magnet trick.
Next time, we’ll talk about installing braces and trying to fill the cracks, or at least strengthen them with the liberal application of titebond. Until next time!
Anyone wanna make me a few dozen cleats?
