Re: Rosonol to clean finger boards?
99.9% of the gunk on a fingerboard can be removed with PLAIN WATER! Water is the universal solvent, and it will remove all the dirt and dead skin that gunk up a board. Just take a damp rag, wipe it down lengthwise, and then crossways to remove the gunk along the frets. Just work quickly, and then wipe it dry. This fine to do on ebony and rosewood boards, and finished maple as well.
If it needs more than that, I'll let it air dry for bit and then use the Dunlop 65 Fretboard Cleaner, and then follow it with the Dunlop 65 Fretboard Conditioner. Gerlitz Guitar Honey is another great product for conditioning fingerboards. There is also a product called Fret Doctor, (bore oil) that is often highly recommended. I've never used it; but I'm going to try it.
On a lacquer-finished maple board, I got in the habit years ago of using a bit of Carnauba Wax to protect the finish, and that worked very well. All of my maple fingerboards these days are finished in poly, so I don't bother with the Carnauba anymore.
Bill