Filling Too-Deep Guitar Nut Slots - on an Ebony Nut!

I was playing my trusty 1931 Martin 0-18T guitar the other night when I noticed it had a slight buzz on the open G (3rd) and A (1st) strings.  The nut slots were cut very deep and now with the drier winter air, the strings were just touching the top of the first fret.

What I need to do is fill the nut slots and recut them.  I've done this one bone a lot, but I think this might be the first time on an ebony nut.

The process really is the same.  I took a hunk of ebony I had on hand, leftover from making a bridge on this same guitar,  and I filed on the edge to make some ebony sawdust.

You could use sandpaper to do this, but you'll find you get sandpaper bits in the sawdust.  Better to use a file I think.

Then sprinkle some of the sawdust into the nut slot in question - here it's the first string's slot - the high A.

All of my pre-war Martins have ebony nuts.  If you think about, ebony makes a good material for nuts - it's hard and dense for good tone but yet it's still easy to work with.

I don't know if Martin used ebony exclusively during this time frame, but I know I've seen a lot of Martin instruments from this era with ebony nuts.

You see that I put some tape on the guitar to protect it during the next step.

As with a bone nut, we hit the ebony dust with a drop of thin CA (super) glue.  I'm using a dropper to get the glue in the slot and not all over the guitar!

Then let it dry for 5-10 minutes.

After the ebony fill has dried, you can use a nut file to deepen or recut the slot as needed.  Or leave it as is.  Whatever is needed.

Slots filed a bit and strung back up.

The slots are deep and wide on this guitar, so it actually took me a few attempts to get the depths just right.  I find that on tenor guitars with a short string length (I think this one is 23 inches), and therefore a more 'flexible' string tension than a standard guitar, you can't go quite as low on nut slots.

Now back to practice!