I'm a newbie, so please bear that in mind. That said, I just have done a fair bit of research here on this forum and on the rest of the 'net before doing I did some rosewood fretboard cleaning and rejuvenating myself. From the little I know, all the above seems to be spot on, except perhaps linseed oil does seem to be ok to use. Here's what I did and what I found out.
My recently acquired used bass is in pretty decent shape but I wanted to clean the gunk off the fretboard. Most of what I read suggested using mild cleansers, rags, and, if needed, non-abrasive pads, etc. Scrub sponges used for deeper cleaning should be finer than what we typically use for dishwashing. More stubborn cases should consider using 0000 grade steel wool. Also, in terms of oils to use, what is needed is a 'drying oil' like linseed or mineral oil (there are others, but not tung or olive oil).
What I did, and it worked well, was a very mild solution of dishwashing liquid and a toothbrush that was not dripping wet to scrub things clean clean as much as I could. Then, I used masking tape to cover up the fretboard markers and using 0000 steel wool I lightly went over the fretboard and also did the frets with a bit more elbow grease.
It came out very clean looking but the fretboard looked a bit dry when done.
Gibson's website article states:
"If you notice that your fretboard has dried out or developed hairline cracks, you may finish this process with Gibson's Luthier's Choice Fretboard Conditioner. Alternately, you can rub one or two drops of oil (mineral, almond or linseed oil) into the fretboard to condition it. Make sure to wipe off excess oil with a soft, dry rag."
I did the oiling with high quality linseed oil applied very sparingly and then wiped off. The rosewood fretboard almost looks new. It has the sheen, polished look of new with out any oiliness/slipperiness. About a week after my initial application I used another two-three drops total, spread out over the entire fretboard. I waited about 20 mins and then wiped clean. I am very happy with how it's turned out. It looks almost new instead of 12 or so years old.
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