I was looking for a dark grained rosewood look, so I tried the stain pen, here are my results. Oiled with Boiled Linseed Oil ~6 months ago. Scrubbed board with acetone, then applied stain. Color it on, wait 10 minutes and wipe it off.

After 6 coats.

Exactly what I was looking for. My one pen hasn't run out of stain yet. if you want black then leather dye/ India ink would probably be the best.
That looks remarkably good. I just have to ask though, do you notice any residue or even grease on the strings? I've personally worn scalloped indents in my fretboard so I wonder how something like this would look in a couple years as well.
..I was watching my death.
Happy it didnt stain the inlays and binding. Did it just wipe right off of that stuff? It looks good!
I'm glad my suggestion helped you.

I've used this stuff before on a guitar I don't use anymore and it's really good. Doesn't wear off either as long as you give it time for the fretboard to take the stain and harden for 48 hours. It comes off inlays with an eraser too.

If you want it black, just leave it on the fretboard for longer. You're not giving the stain enough time to take to the fretboard if you're rubbing it off after only 10 minutes.
Quote by Axelfox
No staining of the inlays or binding. At first I was pretty nervous about it, but everything wiped right off with a rag.

Timbit2006, I decided to again use boiled linseed oil over top of the stain, which has a sealing effect. If you're wearing down the wood I'm sure you would go right through this stuff. No idea how deep the penetration is.

Thanks again for the suggestion toodeep, I was only going to dark brown so I was satisfied with my results.
I've found that the dark walnut stain is a bit better for darkening rosewood without wanting to turn it to ebony. I find it doesn't tend to darken the pores in the rosewood quite so much so the stain is a bit more homogenous. It also means you can leave it on to fully take without worrying it'll just turn the fretboard jet black if that's what you're trying to avoid.
Quote by Axelfox