I've never tried honing a razor on a BBW, so going to give these a run in a little while:
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Three quite different stones it seems. The first is just a little slice of BBW, other two are with coticules. The middle, dark one is notably coarser than the other two:
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So this was interesting. It was my first time playing around at length with BBW, and I tried them mostly on a knife to begin with. But here are some impressions...
BBW is slooooow. Really slow. It's also not particularly fine as an abrasive; these ranged a fair bit, but in terms of cutting they topped out around 7k, with the middle one considerably coarser - maybe 3k. The coarse stone however wasn't really much faster, which I imagine is probably to do with the shape of the abrasive, i.e. kinda rounded or flattened. Frankly they're not very good sharpening stones, and behave far more like quite slow slates than they do cotis.
BBW is however a good polishing stone. Coticules are quite good, but BBW is very good. If you try to ignore my fingerprints on the blade, and the fact that these are indoor nighttime pictures, you can see this here:
It's taking core steel to quite a bright semi-mirror, with nice contrast, but the really impressive part is how even *and shallow* the scratch pattern is on the cladding. I'll do a proper polish on a nice knife, and take some daytime pictures tomorrow, but these stones have a lot of promise.
I only honed the razor on the third of those stones, but it was really rather good. Which probably chimes with most of my other (limited) experience; low-abrasion stones that polish knives well seem to work very nicely on razors, as long as they're not too soft.
To be completely honest I'm slightly surprised that the yellow coticule layer is regarded as a better razor finisher than BBW.