Thread: Tapered barber hone?

I think a slip-stone. Looks like Norton India or similar. Not for razors, IMO.

I have a full set of those. Wonderful stones.

That is a carborundum dual slip stone. Probably 25mm and 12mm.
When clean, the rounded edges are around 1000 grit, but they fill up with metal grit and start to feel like a 4000 grit.
The sides of the stone are usually smoother, up around 6000 grit, so that it doesn't remove your fingerprints while using it.
A little bit of cleaning with a toothbrush and some bar keepers friend will fix it up.

They are supposed to used with oil. I coat mine with mineral oil after cleaning until the stone stops sucking it up and use mineral on the stone while sharpening.

Primary purpose was for sharpening the inside curves of molding planes (ogee, astral, etc.), enshaves, and spoon brace bits.
They were also used for sharpening the inside curves of sweep gouges (rounded wood chisels), crooked knives (hook knives, spoon knives, etc), and anything else that had a rounded inside face.

That's good info and that's about how the surface feels. I didn't try to get it spotless, just a quick wash to get a feel for the surface. I think I'll finish cleaning it soon and play with it a little. Feels like it will cut fast.

Yup, slip stone for carving chisels and other tools.

They make or made them in carborundum and some arks. I have an old very nice translucent ark slip that I have flattened and can be used to finish a razor, but I have larger stones that are easier to use.

A soak in Simple Green or Awesome for a day or two will clean it up, also good for small knives, that one may be too course for razor finishing.

There are coticule slipstones as well.