My good friend and amp guru Mike Fortin brought in a cool piece of shred guitar history with a pedigree: this very axe was formerly owned by famed 80’s shredder Greg Howe, and used on one of his albums. The guitar clearly has been unplayed and in storage for some time, and has a separated skunk stripe crack on the back of the neck which will need repair and then sealed with some coats of Tru-Oil. It will also get a full fret dress in the neck jig.
This shrinkage is usually caused by a combination of dehydration and a poor glue join in this area. The internal pressure from the truss rod isn’t helping it’s case either.
As you can see, it’s a fairly substantial opening, and goes down into the truss rod cavity which can complicate things a little with sealing it.
Ok, so I’ve laid out the basic materials (maple dowel for dust, Titebond Original and low viscosity cyanoacrylate glue, wax paper, neck caul and hard spring clamps) for starting the crack and dent fills.
A banged-up, vintage or reliced body to me is fine, but if it’s one thing I can’t stand it’s big chips or dents on the back of the neck that you can feel while you’re playing. Besides the main huge crack in the skunk stripe, there were a few hairline cracks in the walnut here and there, one decent deep scratch in the maple, and worst was this deep dent where the fibres were crushed significantly inwards on the walnut stripe.
Using the old-school method of lifting dents in wood with steam, which works surprisingly well, often swelling it back to the original surface state and sometimes even higher – allowing the excess to be shaved off level. Before starting the steam using a very hot soldering iron and wet fabric, a sharp X-Acto blade is used to slightly slice into the dent through the finish along the grain to open it up and allow the steam to penetrate easier. But sometimes, depending on how dense the wood fibres were crushed together inwards, it can only be swelled back partially. This was the case here, which recovered about 85%, and still required a tiny about of CA (cyanoacylate glue) to completely level the void and make smooth.
Just above the tip of this pipette you can see how far the steaming process brought back the deep dent, so this will be topped off with CA and also do the hairline crack fills at the same time.
The cracks are first cleaned and de-greased with a few wipes of naptha (lighter fluid) for best adhesion. Hairline cracks are filled with CA in a few applications, allowing extra time between coats to harden fully. It should be noted here that no CA accelerator was used, due to it’s tendency to turn the glue a milky white colour, which we definitely don’t want here. The cracks must be filled completely and above the surface, which is then shaved down flush with a razor scraper after letting dry hard.
Next is prepping the skunk stripe gap for filler. First I clean the slot with a special feeler blade, and then slightly widen the opening with the thicker X-acto knife shown. The crack is then blown out with canned air.
Quickly create some sawdust for filler with a small piece of maple and a big mill file.
A small amount of Titebond Original is mixed with the maple dust to create a ‘glue sauce’.
A tiny amount of water is added, a drop or two at a time while mixing, to dilute and lower the viscosity of the dust/glue slurry to be able to seep deeper into the crack easier. Note: While watering down Titebond or any anaphylactic wood glue is fine for gap filling and a few other uses, it does weaken the final strength and is not recommended for use where maximum strength is required in a high tension area; acoustic bridge and broken headstock reglues are good examples where not to use it.
Ok, so how far to water it down? Tip: When letting drip from a toothpick – 1 drop/sec is good 😉
Carefully run along the full length of the crack…
…quickly use a feeler blade to help work it into the crack…
…and then start working it by pushing the glue into the crack with your finger in a circular motion, moving fairly quickly. Here you can really feel the gritty texture with the maple dust mixed in. You put enough so that it feels maxed-out without too much sink.
Wipe off most of the excess glue leaving a small amount of overspill to cover over the crack area slightly, and then cover with wax paper to prevent squeeze-out from gluing the caul to the neck.
The cork lined neck caul is place over it…
Grip the neck and caul together by hand, flip it over, get a protective wood slab for the fingerboard, and apply the three heavy-duty spring clamps spaced evenly over the length of the crack area. Note: it’s important that you need to have the neck dry in this position, fingerboard up. Utilizing gravity with the crack facing downward, it helps prevent any pooling of glue around the truss rod (not good) and into the crack instead, where we want it. Because of the depth of it, allow this to dry a bit longer than usual – at least 2 days to dry to the core.
To be continued…