Fix a broken nut with baking soda?

Issue 197 August 15, 2013

"Can a broken nut can be fixed with baking soda and super glue?" Lou, a singer here in Athens, Ohio, brought this question to Dan Erlewine (along with the broken nut on his Yamaha guitar). As it turns out, the answer is yes and no...

Video Transcription

Lou Horvath: I've got a question for you. On Saturday, we were playing, and I noticed that I had my guitar in tune, but the low E string kept popping in and out while we were playing and strumming. So taking a look at it, I noticed that the nut was busted on top. I found something that said baking soda and super glue can repair a nut. I'm not sure about that. What can you tell me about it?

The baking soda and super glue trick

Dan Erlewine: [on-screen text reads: Dan Erlewine - Stewart-MacDonald] Before I get into whether or not I can help Lou with a nut on this guitar, here's a little background on baking soda and super glue. The baking soda super glue trick. Mix the two together and you get something hard as a rock. This is regular old household baking soda, and you hit that with a drop of water thin super glue and go off and let it rest for a minute or two and come back and check it out. I gave this about a minute, and it chips like glass. What I use this for is when the nuts slots worn too deep or been cut too deep. It's a least a temporary fix to get the guitar out the door. I'll show you how I do it.

Fixing an ivory nut slot that has been worn too deep

For my demonstration. I'm using an old Washburn guitar from the 1920s. And it's got a lot of troubles with the nut. It's an ivory nut, and the strings have worn way too low over the years, maybe somebody re-cut them. And the first string is laying on the fret. I'm just going to move a couple of strings out of the way and only work on the treble E string slot. Check out the string. It's tied together in a knot to get the most mileage out of that string. I cleaned it up with acetone, get all that grease and dirt out.

Cleaning the nut slot with a slotting file

And now I'm using probably a 40,000 gauge nut slotting file, rolling it back and forth to getting a new material and get rid of that dirt. I want to get down to clean ivory or clean bone, so my glue will stick. That's more acetone and a little bit more filing until it gets clean. If it's not clean, it won't stick. I like this little tip of sliding something under the strings to pull my tape in place. Here I'm using my glue spatula, which is good for putting dust into the slot and packing it down. For dust, I'm going to use a nut that I took out of the drawer. That's an old nut off some other guitar. It's bone, not ivory. And it's the perfect color because it's kind of yellow.

Filling the slot

So I'm filing off bone dust in the area until I get a little pile of it using the smooth side of a file. I want the dust to be small and powdery almost like the baking soda. And get rid of the excess so it won't stick to the tape because that super glue's really thin. It could run down onto it and glue the whole thing together.

I'll start off the edge and let the glue run into the slot. Now I'm packing in more dust and another shot that's took me two times to fill it. And it hardens almost as fast as the baking soda. Something about bone and ivory and super glue. It reacts real quick. Now I'm just going to reshape it a bit, get it smooth. It's all filled. Then I can recut the slot for the string. Hopefully, I can save that original E string. It's vintage.

Filing in the new slot

Make a little impression in the material from the string and follow that with a sharp feather file. And I use a razor saw. I think that's probably a 10,000 gauge precision saw to cut that slot. Getting rid of some of the filing marks with the little 320 grit paper and I should be back in business. That's how fast you can fill a nut slot with bone dust and super glue or baking soda. Ta-da.

Changing out the nut on Lou's guitar

As for Lou's guitar. We'll have to see because it's a plastic nut for one thing. And it seems to be sitting on another plastic nut or a big shelf of plastic. It's been shimmed up. Baking soda will fill plastic but not every plastic. But it's not going to work on a corner. That's too weak. It probably got cracked at some point, and that's why it chipped off. And if you tune that string up, it's going to share off whatever I put on there. This is a case where I go to the drawer and get out a pre-made nut. This tusk one looks like a perfect fit, and we'll find out by knocking out the old one and seeing...

This is great. It slides in as tight as I could ever fit it by hand. I don't even need a file or a chisel. It's getting tight right there, like sliding in a drawer. I'll put on the two outside E string. And if there, all right, it's going to work. That doesn't even need a shim. That's amazing thing. It does not need a baking soda fix if you can change the nut that quick.

Dan Erlewine

Guitar Repairman and Builder