Fret Buzz and Sprout: Singing the winter neck blues

Your guitar was playing great with sweet low action, then suddenly the strings are buzzing against the frets and/or you notice your fingers catching on the fret ends as you move along the fretboard. What’s going on?

Buzz and sprout are problems that crop up in the wintertime, especially for newer guitars. The culprit is low humidity. As you may know, warm air can hold more moisture than cold air, so in the winter outside air is much drier than it is in the summer. When you turn on your home heating system no moisture is added—you are just heating dry air.

A tree trunk is like a bundle of straws (xylem) that suck groundwater up to the trunk to the branches and leaves. The xylem shrink in diameter when the humidity is low and expand when it is high causing boards to expand and contract along their width. Because the xylem runs along the length of the neck, it may become slightly narrower when humidity is low. Metal frets don’t shrink so they may protrude or “sprout” enough to become noticeable in winter.

A “flattop” guitar’s top and bottom actually are built with a slight radius to accommodate expansion and contraction without cracking. As a result the bridge may be higher is warm weather than in cold. If the bridge shrinks low enough, the strings get lower and begin to buzz. Unfortunately, this problem is more common in the best guitars with tops that are as thin as possible for maximum resonance. Lower-end guitars have thicker tops that move hardly at all or plywood tops that are even more stable.

Prevention

It’s tempting to leave your beautiful guitar out and handy on a stand or even hang it on a wall. Don’t do this unless it is in a humidity controlled room or display case. (A controlled room or display case can be a smart strategy if you own multiple guitars.) Guitars, like people, like a relative humidity of about 50 percent. The best defense is to keep your guitar in its case. A case will slow humidity changes, and in milder climates this may be enough. More effective is to keep it in the case with an inexpensive soundhole humidifier. These devices are suspended in the soundhole by the strings. They encase a special sponge that releases moisture when the humidity gets too low or absorb moisture when humidity is high. By the way, if you live in a place with humid summers, air conditioners do a good job of keeping excess humidity at bay. Or for a hundred bucks or so you can get a room dehumidifier that sucks moisture from the air. I use one of these in my shop in warm weather and switch to a humidifier in the winter.

Repair

Fortunately guitars become less susceptible to humidity changes as they age. So if you are experiencing fret sprout or buzz when the guitar is a year or two old, you might just want to live with it until summer. A good trick I’ve used to solve fret buzz is to make a slightly higher “winter saddle.” A saddle is easy enough to make. If you notice the action getting high in the summer, all you have to do is loosen the strings and swap in the original saddle. After a few years the winter saddle will likely become unnecessary.

Fret sprout takes a bit of skill to fix without damaging the guitar finish A good builder or guitar repair tech can carefully re-file and dress the fret ends.