Hando is correct - wet'n'dry paper. Ordinary paper will shed its grit and will not stand-up for long under water without breaking up, but I'm sure you realise that!
You can get it from most hardware shops, DIY shops and even online. Get a good grade, it's cheap enough. Stick to one grading system or you will get confused - for instance, the P systems P1200 is roughly equivalent to the CAMI 600 grit!
The hone you want to lap will dictate how low you go - I usually start at 150, followed by240, 325, 600 and 800.
A stout glass plate that is level and true or a slab of marble is needed. Put a small puddle of water on the base and lay the sandpaper face-up on it - this will make sure the suction sticks the paper to the base so the paper does not move. Pour another puddle on the paper and begin up/down lapping movements. Add water to remove the slurry and keep the hone moving easily. After a bit, take the hone of the paper, wipe it dry and draw pencil cross-hatch marks on it. Put it back on the paper and make a few laps, then look at the grid marks you drew - where they have worn away was a high spot, where they haven't is a low spot. If you see any marks, keep lapping. When they have all gone, draw the pattern on again once more and try a few laps, just to enure that the hone is level and that the slurry hasn't just removed the marks. After that you can progress quite rapidly through the grades, lapping just enough so that the score marks from the previous rougher grit have all gone.
This takes forever and a day on very hard hones, those with a lot of dmage and most natural hones - or it feels like it does! Seriously, lapping a hard natural for a couple of hours and seeing you need at least anothe hour or two and more sheets of paper is no joke. A much quicker way is using the silicon oxide grit sold by lapidary stores for tumbling pebbles, polishing, etc. You need a level and true base again (I use sheet glass) and make a paste up from the grit by adding water.
All the Best,
Neil
