Cleaning and Polishing Your Guitar
What are the best cleaners and polishes to use on my guitar?
There has been a great deal written about cleaners and polishes for guitar finishes, and each guitar player you ask will have a different opinion about them. Most luthiers (the people who build guitars) will tell you that the best cleaner is simply a soft, damp cotton cloth. Wipe skin oils and smudges off your guitar with one and then use a soft, dry one to absorb excess moisture and buff. Old baby diapers that have been washed many times serve this task perfectly. If you have any trepidation about using diapers, there is a multitude of microfiber cleaning cloths on the market that are quite soft and serviceable. Just be sure not to use the knobby ones that are normally used for dusting furniture, because the rough texture of those will leave scratches in the finish of your fine guitar. You can use the flat, shiny cloths or the chamois-like ones. If the damp cloth/dry cloth method doesn't remove the built-up gunk, then perhaps you need to address the situation with a cleaner and polish.
There are many guitar-cleaning solutions and polishes that can clean and shine your guitar if you feel that a damp cloth is not quite effective enough. Some of the cleaners will remove gunk, fingerprints, smudges and skin-oil buildup. Some polishes are designed to fill superficial scratches in a nitrocellulose or catalyzed lacquer finish, or at least make them less obvious. You can find polishes that will buff out to an incredible shine. But before you buy, read the label to see what’s in it. If there is silicone in the formula, look for something else that is silicone free. Silicone will take grime off your guitar, as well as finish, and it can build up in out-of-the-way places, such as the neck-heel joint or along the edge of the bridge. Many polishes contain carnauba wax, which is safe for most finishes, and will leave a deep, rich shine. On guitars that have polyester finishes, you can even use a light polish designed for use on shiny plastics. It's always prudent to do a little test patch in an out-of-the-way spot on the guitar before you slather polish all over it.
If the fretboard of your guitar or synth is made of real wood, you can clean it lightly with 0000 steel wool. Wipe off the little steel filings, and then rub a few drops of fretboard oil into it. Just use a few drops here and there, let it set for a minute or two, and then wipe the fretboard with a clean cloth. You only need to do this once a year, preferably in the wintertime. This should keep your fretboard clean, conditioned and crack free.