I just bought an old barber hone off eBay. The box says "Steinmetz professional barber hone," it's about 2"x5", and it has two sides (it came with instructions, too). The finishing side has some sort of build-up of gunk on it that seems to scratch off with my fingernail. (I would include some pictures, but the only camera I have right now is my phone and that won't do much good.)

So I guess my main question is, what should I do to get this hone good to go? Should I just de-gunk it, or lap it, or just stare at it and hope it'll hone my razor by itself?

Thanks,
Nick