Because an acoustic guitar’s fingerboard generally doesn’t have finish applied to it, it should be cleaned with a method slightly different from the one you use on the body. A few companies make cleaners for just this purpose (Dunlop’s Fingerboard Cleaner and Dean Markley’s Love Potion #15 are two examples), and you can also use a bit of very fine (0000-grade) steel wool to remove fingerboard grime. Steel wool works particularly well on seriously grungy fingerboards, and you can also use it to clean your frets. Be sure to move the steel wool parallel with the wood grain, however, to minimize scratching. If your frets still look tarnished after cleaning the fingerboard, you might try Planet Waves’ Fret Polishing System, which consists of five sheets of polishing paper and protective templates to keep the wood areas of the fingerboard from becoming scratched.
To complete your fingerboard cleaning and maintenance, apply a dab of lemon or mineral oil (or any of the various fingerboard conditioners made to “feed” the wood) to a soft cloth and rub it into the wood. Most manufacturers of guitar-maintenance products offer a version of lemon oil for this purpose. Don’t overdo it—excess oil will take a long time to dry and may reverse your efforts by attracting dust and dirt to the newly cleaned fingerboard. (You don’t need to do this often; once a year is plenty. I often go several years before applying oil to a fingerboard.).
Excerpted from Acoustic Guitar magazine, December 2009