How to Clean Your Guitar
A soft cloth is the best thing to use to polish and clean guitars. Many manufacturers of musical instrument accessories offer special polishing cloths made specifically for use on guitars. But an old 100 percent cotton T-shirt makes a great guitar wiping tool too, and the more it has been laundered the freer it will be from lint. Beware of paper towels, which can actually scratch a fine guitar’s finish, especially if it’s lacquer or shellac French polish.
As you wipe down your guitar, particularly the top and back, you may notice some spots that don’t come perfectly clean. Fingerprints, smudges, and other dirt may respond well to a trace of moisture. “Huff” some warm breath on the surface the way you would if you were about to wipe the inside of your car’s windshield. Just that little bit of condensation may be enough moisture to allow you to wipe the offending area clean. If you need a bit more cleaning power, try moistening the wiping cloth with a little mild detergent in water. Wet the cloth, not the guitar. That way you’ll be able to control how much water actually gets on the surface. The idea is to use as little moisture as possible, to avoid getting it into any tiny voids in the finish. Follow the damp wiping by buffing with a dry cloth to remove any streaks.
You’ll also find many commercial guitar polishes and cleaners on the market, which are basically three different types: water-based cleaners; creamy, water-based cleaners with very fine abrasives; and oils. Water-based cleaners (which look semitransparent in the bottle) should be sprayed on the cloth rather than the instrument and will clean up water-soluble dirt best. The creamy polishes may have a slight abrasive and are best avoided if you have a matte-finished guitar (too much polishing can cause a semigloss finish to become shiny in patches). Oils will remove oily smudges but may not have any effect on water-soluble dirt.
Excerpted from Acoustic Guitar Care and Maintenance