It’s inevitable as the tide: Consistent steel-to-steel contact between strings and frets will take its toll, so much that a worn fret can take on the appearance of a nut, as shown here.

As guitarists, we love knowing that our guitars sound better as they age. Can you think of many other tangible items for which that’s true? Maybe a baseball mitt or a cast-iron pan improve with years, but beyond that, it’s a pretty short list. Most things simply wear out and their performance deteriorates. Guitars, on the other hand, improve with every chord and practice session.

There are, however, a few parts of the guitar that do wear out and need regular maintenance. Among those parts are the frets, which we use constantly.

Frets are like the brakes in my truck. They’re quite necessary, and I’m glad I have them. But each time I press that brake pedal, they wear out a little bit. For steel-string guitars, the metal-on-metal contact that comes with every fretted note wears on both the frets and the strings. And just like with brakes, there are many factors that determine how fast these parts deteriorate.

It’s easy to imagine how when one metal rubs against another, the softer of the two will lose. So, when we think of frets and strings, it seems logical to assume that the harder the string, the more the fret wears down. But strings are not made from just one metal or alloy. We’ve got plain carbon-steel strings, bronze- and brass-alloy wound strings, nickel alloys, and stainless steel. And they all vary in their hardness. String companies have also produced strings wound with a single wire, two wires, and even a round wire covered by a layer of flat-metal ribbon, which all wear frets differently, too.

The player’s the thing. Aside from fret size, hardness, and string type, there are aspects of the player’s technique that also contribute to fret wear. The more firmly the string is pressed to the fret, the more the fret will grind down. Another major culprit is bending. While the fret-to-string contact is spread over a wider area of the fret, the grinding action between the fret and string is exaggerated when a player bends a note. In areas of the fretboard where the strings are bent less frequently—such as the lower wound strings and frets near the nut—you’ll notice more clearly defined divots rather than the sloping valleys under the commonly bent high strings.

There remains an invisible but powerful vibration that travels the length of the string, dragging it across the fret like the teeth of a file.

It’s probably no surprise that variations in string hardness and fretting-hand technique would directly affect the lifespan of a fret. But what about the strumming hand? While less obvious, a player’s string attack can have an even more significant impact on fret life. That’s because a string’s vibration doesn’t totally stop at the fret. There remains an invisible but powerful vibration that travels the length of the string, dragging it across the fret like the teeth of a file. Coupled with the string’s tendency to move sideways in response to transverse vibration, playing hard usually wears frets out more quickly. Most guitarists also tend to practice and perform the same songs repeatedly, which wears out certain spots on the fretboard more quickly than others.

Players who play fast and hard tend to go through frets more quickly than those with a delicate touch—just like the brakes in your car. That said, I don’t think you should change your approach just to avoid wearing out the frets. Play with the pick and strings you like, and simply maintain your frets as needed. Keep in mind, however, that this is just a short list of factors that impact fret wear. Other minute details, like the acidity or alkalinity of a player’s perspiration, make a difference too.

The squeaky wheel? So, what do worn-out frets sound like? Do they squeal the way my truck does when approaching a stop sign? Not quite. Most often, players will hear buzzing or rattling from the strings. The more commonly played notes dig deeper grooves into their respective frets, effectively reducing the clearance between the string and the fret immediately in front of the worn one. This causes the string to rattle as it vibrates. Some players also notice that when they bend a string, their notes begin to fade out with less sustain than before.

The good news is that it’s easy to keep your frets in great shape. Typically, there is enough metal in the bead of the fret (imagine the head of a nail) to allow a luthier to grind the frets to a uniform height and re-round them, and provide a consistent contact surface for the strings several times before the frets wear too low to play comfortably. (It’s like resurfacing a car’s brake rotors.) Even when the time comes for full fret replacement, it’s a routine task for any seasoned repairperson.

I’ll leave you this month with a fun fact, courtesy of ace repair-tech Joe Glaser. Frets tend to harden as they get older. It comes from all that metal-on-metal hammering action, which, over time, slows down the rate of wear. So, be kind to those poor frets. They’re trying their best to keep up.