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This stuff was made for repairing ivory!
Light Cure Nut Fill
© Frank Ford, 2/26/02; Photos by FF

These days Dan Erlewine and I have been trying to outdo each other on innovative repair techniques. So, when one of us tells the other he's about to get into something new, we just say, "Get some for me, too." That's the way it went when he told me he borrowed a light cure machine from his dentist, and was planning to get one of his own for filling nut slots. If you have great teeth and don't know about this machine, well, suffice it to say it's a little high intensity light and a chemical system that can catalyze a permanent filling in a matter of seconds. The only downside is these things are expensive - check with your dentist on that! Or, do a quick Internet search for "3M Light Cure."

The patient is a Martin guitar, style 00-42, made in the late 1890s. It's suffering from lowered nut slots.
The slots for the 4th, 5th, and 6th strings are so low that the strings fret out on the first fret. The first three string slots are just fine. So, to avoid having to remove and shim the nut from the bass side, where it would be noticeable, I chose to fill the nut slots.
First, I used my smallest round bur in my Dremel tool to "undercut" the channel just a trifle to provide a good mechanical bond for the fill material.
Next, an application of a special dilute phosphoric acid etch. This chemical raises tiny fibers, allowing for an even better bond of the adhesive.
A quick wipe with my frayed toothpick brush to remove excess etch.
And, using the same little toothpick, I added in a bit of clear adhesive.
Now, out comes the light saber, which has a VERY high intensity beam of visible (blue) light to cure the adhesive. It only takes about ten seconds of light exposure for a full cure. That little yellow shield is there to keep me from going blind as I use this lamp.
Then, using a tiny caulking gun loaded with ivory colored fill material, I can load up the string slot. As you might expect, this material is available in virtually any tooth colored shade, so I selected some to match this elephant tooth.
I used the shank of an appropriate size drill bit to form the compound into shape and press it well into the cavity.
Then, twenty seconds of exposure to that blue light, and the fill was hard. Really hard.
As I filed it to the proper height, I was amazed at how much harder the fill is than the surrounding ivory. This fill will wear well.
Job done. It's a permanent fill that will be likely to outwear the original material and it's virtually invisible. This is another example of how the world of high tech can be directly beneficial to those of us who perform strictly traditional craft.

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