I've read different post about the various products used and if they are even worth the effort, (pertaining to dying a fingerboard). I've drawn nothing conclusive yet. But that's what I'm wanting to do. I'm not interested in replacing the fingerboard because it's brand new and works very well, (it's made from Jatoba). For me it's just a question of aesthetics. I made my own nut from ebony and the tailpiece is from Gollihur Music, (outstanding quality). Looks good thus far but the Jatoba fingerboard must match. Any suggestions? (Please don't suggest replacing the FB that's out of the question). Thanks folks!
Not sure this is relevant as I don't play/own an upright, but I wanted to darken the rosewood on my Fender Jazz, and was a bit apprehensive of using anything to dark and permanent. And fearing dyeing parts I didn't want to dye. I ended up using "Old English Scratch Cover for Dark Wood."
I was told it was basically mineral oil and a little bit of stain. It won't drastically dye the fretboard, not with just one use, but if you apply it every couple of months the way you would oil a fretboard it will make it richer and darker after just a couple uses.
Pros:
It's cheap, couple bucks.
Can buy it locally, sold at Home depot, other hardware stores, possibly even some grocery stores.
Can use it for other household uses after you are done using on fretboard.
Goes on easily, wipes off easily, use it in place of lemon oil for oiling fretboard.
Becuase it isn't a dye perse you can fine tune how dark you want the fretboard. Just stop using it when the fretboard reaches the darkness you want.
I only tried it on my one fretboard, but it seems like a good alternative to using a very dark dye that you have no control over how dark it may get with even just one applicaiton.