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.
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.
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.
Then let it dry for 5-10 minutes.
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!