Q: I have a question about fretboard oil. Is it a good idea, or is it snake oil? Once or twice a year, I clean the frets on my guitar and oil the fretboard. I do this to prevent the fretboard from drying out and possibly cracking. Recently, I’ve been reading posts on forums where people are saying that oiling does nothing but make a fretboard look nice for a short period of time. I’ve always assumed that the oil would soak into the fretboard and act as a moisturizer. Am I wrong? What are your feelings on oiling a guitar fretboard?
—Ryan, Milwaukee, Wisconsin
A: This is a great question. We do so much in the hopes that our guitars will sound their best, look their best, and age as gracefully as possible, and it can be frustrating to hear claims that something that seems to make so much sense isn’t doing anything. There are several ways to think about this question. Fingerboards tend to be made out of dense, hard woods. Some woods, like rosewood, are oily themselves. In fact, a light polish on a buffing wheel brings up some of the oil in a rosewood fingerboard, which gives it depth and makes it look shiny. Let’s talk about wood for a moment.
I hope this answer isn’t too disappointing. In fact, I use fingerboard oil whenever I do a setup, before stringing it back up again. It is satisfying to really see the beauty and luster of a good-looking piece of wood. Anything that increases your enjoyment of your guitar without doing damage is cool by me! The only way to be sure your fingerboard won’t crack is to tune up your time machine, go to where rosewood trees grow, and make sure the tree that is your future guitar is sectioned well, aged, and dried properly. If you don’t have a time machine, here’s what you can do: humidify your guitar whenever the air is dry, and moisturize the fingerboard with oil to keep it looking great.
If what we are trying to do is prevent cracks, let’s think about what causes them. We know that if a piece of wood isn’t aged long enough or dried slowly enough, it can continue to change shape even after it’s glued onto another piece of wood. Over time, this distortion, especially while pulling against a glue joint, can be enough to cause a piece of wood to crack. Further, because all wood does some amount of swelling and shrinking—even well-aged and -dried wood—we want to prevent that from being too extreme. For most of us, this means we need to make sure that our guitars don’t get dry. Dryness is the only sure way I know to get a crack in your fingerboard. So, no, wood doesn’t need anything smeared on it to keep it from cracking. All it needs is a stable, properly humidified environment.
But don’t let that keep you from doing something that you like to do! Fingerboard oil can indeed condition, moisturize, and beautify wood. Almost all versions of fingerboard oil are made of mineral oil, including lemon oil, which is just a light mineral oil that may have a lemon scent added. Some modern formulations may have wax or silicone in them and these are the ones to steer clear of. The oils with wax or silicone additives can build up on the surface of wood, attracting dust and schmutz; so while the wood will appear shiny and smooth when it is first applied, it doesn’t take long for the fingerboard to look dingy and dirty. Often I find myself cleaning this stuff off of boards that come into the shop.
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Mamie Minch is the co-owner of Brooklyn Lutherie and an active blues performer.
This article originally appeared in the January 2019 issue of Acoustic Guitar magazine.