February 14, 2017
While uncommon, loose or missing fingerboard inlays are not unheard of. A fingerboard inlay can sometimes be worked loose if the instrument is subjected to extreme humidity or temperature fluctuations, causing the board to expand and contract. Over time, this expansion and contraction can work an inlay loose. This is more common on older instruments, of course, and less common on newer ones, like this Guild. I suspect that these inlays on this instrument were not glued very well at the time of production, and a closer inspection reveals a few inlays further up the board that were loose as well. I wicked some super glue into the channels around these inlays and leveled them off to insure they’d stay put.
I’ll be replacing two missing pieces of inlay that fell out of the fingerboard behind the 3rd fret. As you can see, there’s a bit of finger gunk and glue build up inside the inlay channels. I cleaned the channels out with an x-acto knife and a naphtha soaked q-tip before continuing.
For reference, here’s a photo of the fluted diamond shaped inlays at the 7th fret which I will be trying to replicate.
Here, I’m comparing different scrap pieces of pearl to the surrounding inlays, in an attempt to find a good color match.
Here, I’ve found two suitable pieces. The white balance on my camera was a bit off; in reality, these pieces of inlay are a bluish silvery tint, nearly identical in color to the inlays at the 1st and 5th frets.
First, I rough cut the inlay close to size on the disk sander. Then, I slowly thin the sides down with a sanding stick, until it fits snugly into the cavity. I want to make sure that it’s sitting on the bottom of the channel, and not getting hung up on the edges. In the above photo, one corner is in all the way, but the opposite side is hung up on the edge. If I were to call this good enough, I would likely sand through the inlay later on.
After I’ve achieve a proper fit, I use my nut files to cut the flutes in the diamond shaped piece of pearl I have created. Then, I begin to prepare the board for installation of the inlay. In this photo, I’m coating the surrounding surface of the board with wax. This is to ensure that the adhesive I’m using, which in this case will be cyanoacrylate, or super glue, does not stick to the fingerboard.
Then, I apply some medium viscosity super glue inside the channel, and press the inlay into place. Next, I fill the small gaps between the inlay and the board. In this case, I’m using fine ebony sawdust, which I pour over the inlay and pack into the gaps. Then, I wick thin viscosity cyanoacrylate into the dust. The glue sucks the ebony dust into any gaps that are present, and hardens there, but it will not stick to the surrounding surface where I have applied the wax. This makes my clean up a lot easier. Sometimes, epoxy tinted with lamp black or charcoal is used as an inlay filler on ebony, but I prefer superglue and wood dust. I save fine sawdust from ebony, as well as from different species and colors or rosewoods in film canisters, so I have a few options to pick from when trying to match the color of my filler to the surrounding wood.
This technique of filling gaps around inlays is more noticeable on lower cost import instruments. In some cases, no attempt at all is made to achieve a close, seamless fit; rather, a large channel is cut, the inlay is dropped in, and filler is liberally poured in around it and leveled off later.
I let the super glue dry without using accelerator. Accelerator cures super glue almost instantly, but it does so through the use of a chemical reaction that produces heat and fumes, causing the glue to foam and bubble somewhat before hardening. This can create an unsightly glue line, so I try to avoid using accelerator in this case. Once the glue is dry, I begin to level it off, using sand paper and a hard sanding block. I mask off the frets, to avoid scratching them, and I make sure to sand with the grain of the fingerboard, to avoid any unsightly cross grain scratches.
Next, I follow the same steps as before to prepare another diamond inlay for installation.
When I’m finished, I sand the fingerboard around the inlays to remove any leftover wax and glue. I use progressively finer grits of sandpaper until I have matched the smoothness of the rest of the fingerboard. Then, I buff the board and frets with 0000 steel wool, and apply Dr Ducks Ax Wax.
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