GAAHHH, I HATE when I type up a whole page and then loose it! AAAAGGGHHHH

So, you get the monosyllabic summary.

Case 1... jade or sintered hones will be mechanically abraded down to a mean surface roughness that relates to its internal grain size (thus two sintered ruby stones or ceramic crock sticks may insist on behaving differently because they have different internal grain sizes). Once it is broken in like that, it will be at its optimum. a dressing stick or diamond plate will need to be used periodically to expose fresh grain after this type of hone begins to loose its cutting ability.

Glass hones are amorphous and have no internal grain so they simply need to be replaced, refrosted, resandblasted or re-etched to their desired roughness (I suppose if someone grew a huge ruby crystal, or stole the rod out of a big ruby laser, they could use a diamond and make a file out of it, in which case it would act like a glass file).

Case 3 is how waterstones generally work... the binder is intended to give way as fast as the grit dulls. With synthetics we get a grit number and it we ask around we may learn a stone's relative hardness (equivalent to the "grade" of an industrial grindstone rather than the moh's hardness of the abrasive), but we still don't know how a stone will work 'til we try it with a particular steel (I've got a lot of stones... here are a few of them:


and each steel seems to have its favorite stones)

I've seen photomicrographs of tennen toishi (natural Japanese whetstones) and the grit appeared to be made of flattish flakes. I have a feeling that these tend to shave off the high spots on steel rather than plow furrows in it like hard football shaped crystals of synthetic abrasive... This may have something to do with sword polishers only using natural stones saying that they reveal the activity in the steel rather than plowing it under and obscuring it like a synthetic stones do.

On a similar note, here is a photo of some 3M silicon carbide microfinishing film:



Notice the flattish blade like fragments? Well, even though SiC is not recommended for grinding ferrous materials, I suppose you could use it for low pressure hand polishing. Wonder if it would leave a different surface finish than Al2O3 or diamond???


Some of the artificial stones, like the Kitayama 8000, mix in some natural stone poweder and the slurry is supposed to crush down to closer to 12,000 grit so with a little care, it can produce a finer finish. My natural aoto is like that... I'd estimate it to be about 1.5k if I use it under running water, but if I let the slurry accumulate, it acts more like 3k or more.