Great question, this is one i get asked a lot. There are basically two types of maple fretboards out there.
1. Some maple boards have a thin finish of them, similar to the finish on your guitars body. For these, you can use the same guitar polish (make sure its silicon free) that you would use on the rest of your guitar. Zippo lighter fluid is also great to use on these boards. As strange as it sounds, zippo lighter fluid is one of the safest solvents to use on guitar finishes.
2. The other type are raw maple boards. The same way that most rosewood or ebony boards are raw wood. These are a little trickier as maple stains really easily. You don’t want to end up with a dirtier board than when you started. Avoid using any kind of oils. Oils will take that grime and gunk on the fretboard and seep it into the grain, as well as stain the maple.
A small amount of hand soap diluted in warm water is safe and works great. Use it sparingly on a clean cloth. You don’t want to soak the board, you want to use just enough to take off the grime. Use a second, dry cloth and a fair amount of elbow grease afterwards to clean off any residue.
About Mike Han
As a self taught guitar tech, Mike worked for many years as the on site guitar repairer for Steves Guitar Sales in Australia, before venturing off with his own successful repairs shop, Mikes Guitar Garage: Repairs and Setups. As one of the only guitar repair specialty shops in Sydney, Mikes Guitar Garage is always busy, yet still prides itself on fast turnaround time and attention to detail.
Mike is a also a working musician and has played in many various cover and tribute bands.