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Taylor 12-string
Crack Repair
© Frank Ford, 7/10/02; Photos by FF

This Taylor 355 was dropped a fair distance and suffered a few nasty cracks.
The treble side looked pretty bad.
And, the top didn't look all that much better
As you look closer at the top damage, you'll notice that the top not only cracked, but is now overhanging the binding by a fraction of an inch. This guitar had been dropped more or less on its end, crunching the spruce at the margin as well as cracking it.
As I worked on the side, I didn't want to get any dirt into the top cracks, so I protected them with a bit of wide sign maker's low tack "transfer tape."
Here's the area of the side where it hit an object directly as the guitar took a second bounce.
Nasty as the crack looked, it was not difficult to realign and clamp with some nice fresh hide glue. Since all the side damage was in a curved area of the body, it was not necessary to reinforce the inside. The arch is a well known structural form, and even with this thin mahogany side, it provided all the stiffness needed once the crack was glued up. Had this crack extended into a flat area of the side, such as the waist area of a dreadnought body, then it would certainly have needed some internal reinforcement to keep it rigid.
In order to secure that loose flake of mahogany, I wedged it inward from the bar of the clamp, with a bit of waxed paper to avoid gluing the wedge to the guitar.
I have a long spreader clamp that's really just a piece of threaded rod and a section of pipe, fitted with wooden ends.
There's a nut soldered to the end of the pipe so I can screw the pipe and lengthen or shorten the clamp.
Inside the guitar, I applied about as much pressure as I needed to stretch the top edge of the sides outward so the top would fit back within the purfling
I still had to cut the purfling away from the spruce because there were so many crushed fibers wedged underneath. Even with the sides back in alignment, the spruce wouldn't press back where it had been.
This is the end of my little circular backsaw. It cuts a .006" kerf. I cut the binding and the purfling right on the center line of the top so when I glued them back in place, the pieces would look as though they had originally been joined there.
Once I pulled the purfling away, it was easy to see the flakes of damaged spruce. With those flakes out of the way, it would be no problem to glue the top back nice and flat.
I used my longest 1/4" steel probe rod to make a crack lifter that would reach way down inside the guitar where I couldn't get my hand.
A simple hole in the bench serves as my bending fixture.
Now, prying against the back brace, I was able to lift the cracked areas open so I could put in some clear hide glue.
Transparent hide glue is the least likely to stain blond spruce, so it was the obvious choice for gluing up these top cracks. They were very clean cracks without a trace of dirt, so I was confident that if I kept my hands clean I'd get a nearly invisible glue joint.
I approached each of the two cracks separately. My long "take apart clamp" was just about the only thing I could use to reach the end of the crack, and I used it along with a few others to clamp the crack flat.
You can see the heavy acrylic cauls on top. On the inside I used some spruce reinforcement patches to stabilize and flatten the crack, gluing them at the same time as I glued each crack.
I glued the top back flat against the lining where it had broken free.
Titebond was my glue of choice for reattaching the binding. Easy to clean up, it also adheres well to the wood fibers still attached to the inside edges of the plastic binding.
A drip or two of medium viscosity cyanoacrylate provided a decent fill for that tiny gap in the binding.
Back to the side repair, I sanded the repaired area level.
And, sure enough, I sanded right through a bit of the original stain because there was a bit of misalignment in the "impact zone." The nominal thickness of most guitar finish is on the order of five or six thousandths of an inch, so it's not surprising to have pieces sticking up enough so the finish gets sanded off when the area is leveled for retouching.
A bit of brown stain in that light area made all the difference.
I used more of that low tack sign makers tape to mask off the entire guitar body, leaving only the treble side exposed.
Taylor guitars are finished with a catalyze polymer which is impervious to any solvent in my arsenal, so to promote good adhesion, I turned to traditional shellac, which sticks well to surfaces of all kinds. A quick wipe with 1-lb. cut clear shellac provided a surface onto which I could spray regular nitrocellulose lacquer with confidence.
Before actually spraying, I drop-filled a couple of tiny holes that were revealed when I wiped on the shellac. Then, I applied a couple of coats of clear lacquer, allowed them about a week to dry, sanded the side level once again, and sprayed the final coat of low gloss lacquer to match the original finish.
With some 2400 grit Micro Mesh, I "broke" the edge between new and old finish at the binding.
The end area got the same treatment, so there wouldn't be a ridge between the old and new.
The top had come out very level, so it needed only some very fine sanding to clean up the actual edges of the cracks. In fact, the cracks were so tight that additional finish was unnecessary.
After buffing, the top looked just fine.
And, you'd hardly notice the repaired side, either.

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