I'm putting new pups into my guitar so I've taken off the strings, removed the bridge and now I have access to the cavity and fretboard. I'm using this chance to clean my guitar completely. I'm just wondering what's the best household substance to clean the gunk off my fretboard. It's bound rosewood. I don't have the time or money to get a specialised cleaner and I'm just wondering if there's a better alternative to warm water.

i just scrape it off with a credit card or something similar
and clean the fret board with a microfiber cloth if you have some lemon oil you can add that to help hydrate the woodand such