What is wrong with the nut ? String are too close to the fret board ?
I use dust from the top of the nut and crazy glue
Here he use baking soda;
Repairing Worn Slots
Wear. As guitar nuts age, they can feel quite comfortable but the slots can become low enough to cause an irritating buzz on the open strings and produce a loss in tone.
It’s pretty easy to determine which ones are the culprits, they’re the ones that buzz when you give them a good open pluck and sometimes you can actually see them riding the first fret.
Usually it’s only one or two strings which show these symptoms and to keep things simple, we’ll deal with rebuilding string height on a limited level.
A standard remedy for this problem is to use Krazy Glue and baking soda. The recipe works fine, but I’m a fan of using the same material the nut is made of.
I keep a handy supply of bone dust available as it tends to cover most instances of string slot repairs nicely. We’ll also need something to cut the slots with.