While tuning, you may hear a ping! as a particular string suddenly increases in pitch. You may also hear the pitch change after bending a note or strumming a chord. This unwanted pitch change is often caused by the string binding in the nut slot.
Luckily, the fix is extremely quick and simple. Use powdered graphite, or ... in a pinch ... an ordinary lead pencil!
Slip the string out of the slot in the nut. Better yet, do this when the guitar has its strings removed. Rub the side of the sharpened pencil tip across the slots in the nut. The graphite powder will trickle down into the nut slots and keep them lubricated. When the string is replaced in the slot, friction will be greatly reduced. The result: no more annoying ping!
Pencil lead (actually graphite) comes in various hardness grades. The lower the number, the softer the graphite. Go for a lower number, such as a 2, to avoid scratching the nut material. Be sure to slide the side of the tip -- not the sharp point itself -- of the sharpened lead point across the nut slot.
Some guitars are more prone to this annoying behavior than others. Many of my favorite Gibson® SG® axes have had this condition, because the traditional Gibson heastock shape doesn't result in a straight string pull from the tuners to the nut. Some Fender® models must have had this problem, too, which is likely why the Strat® Plus and Deluxe models with humbuckers feature a roller nut.
Another method is to swap the nut on your guitar for one that already has graphite impregnated throughout it. Your local luthier can do this for you. Or if you're the handyman type, you can do this yourself if you have the proper tools.
But if you're like most of us, and you don't want to destroy any possible future sale value of your instrument, there are several commercial products that work great to use with your existing nut.
One product in particular, GHS GraphitAll Guitar Lubricant, works great and is also white in color, so it basically turns invisible on your guitar nut! A friend of our webmaster uses it on his Fender instruments especially, since Fender uses white or bone-colored nuts on most of their American-made products. He finds that it stays in place, doesn't discolor the nut, and cleans up easily if he accidentally puts a little too much in the nut slot.
So there you have it, a do-it-yourself method, a take-it-to-your-favorite luthier method, and an inexpensive commercial product that will get rid of those annoying tuning problems forever!
Nut lubricant and replacement nut products we found on the web:
Big Bends Nut Sauce Tuning Lubricant
Graph Tech Trem-Nut Blank for Stratocaster
Graph Tech Slotted Trem-Nut with 1/4" String Spacing
Graph Tech Slotted Trem-Nut for Stratocaster
Fender Accs. LSR Roller Nut
Fender Nut Blanks for Vintage Strat / Tele
Graph Tech Slotted Trem-Nut for Jumbo Guitar
Graph Tech Trem-Nut Blank Jumbo
Fender American Standard Precision Bass Nut