Thread: Natural Stones Approximate Grit

Wow, Gssixgunn talking grit ratings on a natural is a switch, eh? Interesting theoretical topic, though. I went with 20k. But Steve, I gotta try one of these 30k JNat edges at some point. Lately I'm getting more and more into naturals, so I'm saving my pennies and watching here, Etsy and the Bay.

Right now, I'm jonesin' real bad for 3 rocks: one of Keith Johnson's complete Shoubodani JNat kits (I've bought and sold a couple already), a nice full-sized Escher and a foot-long primitive cut SB or Trans Arkie. I mean like aircraft- carrier sized. I want one that's like the center piece of a coffee table-I mean those things are seriously cool, and relatively cheap compared to their full-dressed stones (referring to Dan's). And when I need a narrower Arkie, I can just use my 4x2 vintage Norton banded trans ark.

And I'm still waiting on my Zulu while I play with TC's. I honestly think I'm more into hones now than the razors themselves!

Depending on the razor, the ones I have produce edges that feel similar to 16-20k range. I went with 20k.

Originally Posted by Scipio

More comfortable does not always mean sharper.

I am interested in this comment and the basis for it.

So many different angles to go here. If we are talking actual grit size I don’t think they are that small. I think an Arkansas is around a 1200 grit equivalent but due to the binder (or lack there of) it can act like a much higher grit stone as it burnishes. How the stone cuts and how the cutting particles are arranged can also have a dramatic effect. Then you get into another ball park entirely when you talk about “friable” grit (if that’s ever been proven I don’t know). Or you can talk about the perceived edge you finish with and the shave result.

For me, the perceived Edge’s of some of my thuringian and jnat edges have been over 12k and there is another difficulty- I don’t know that I can tell the difference between a 15k edge and a 16k or 20k edge for that matter. If I’m honest. I think I can but.....yeah.

The shape of the edge, I believe, has a profound effect in the end too. A rounder (think splitting maul or apple seed) edge is much more comfortable but not necessarily more sharp. There’s another can o worms too.

Of course this is only my current, imagined, subjective, opinion. I have very little objective scientific basis for any of it. So take it for what it’s worth.

PS. I vote for 20k although it’s only a subjective guess.

Maybe sky is the limit, but I think we need to have the additional qualifier that there has to be cutting speed that is practical too. While cutting speed and grit are different, but to answer this question they kind of need to be considered together. What I mean is that no doubt there is some natural that is in the 30k or 50k range but just isn't practical to use because you'd be sitting there all day rubbing your razor back and forth. (I don't know what that stone would be, I'm just being speculative there).

Originally Posted by Steve56

I am interested in this comment and the basis for it.

Wouldn't the classic example of this be a coticule? While they don't typically get a razor as keen as any number of other hones (many synthetics, charnley forest, thurgians, etc), many people nonetheless prefer the edges because of how gentle and smooth they are.

Originally Posted by Steel

So many different angles to go here. If we are talking actual grit size I don’t think they are that small. I think an Arkansas is around a 1200 grit equivalent but due to the binder (or lack there of) it can act like a much higher grit stone as it burnishes. How the stone cuts and how the cutting particles are arranged can also have a dramatic effect. Then you get into another ball park entirely when you talk about “friable” grit (if that’s ever been proven I don’t know). Or you can talk about the perceived edge you finish with and the shave result.

For me, the perceived Edge’s of some of my thuringian and jnat edges have been over 12k and there is another difficulty- I don’t know that I can tell the difference between a 15k edge and a 16k or 20k edge for that matter. If I’m honest. I think I can but.....yeah.

The shape of the edge, I believe, has a profound effect in the end too. A rounder (think splitting maul or apple seed) edge is much more comfortable but not necessarily more sharp. There’s another can o worms too.

Of course this is only my current, imagined, subjective, opinion. I have very little objective scientific basis for any of it. So take it for what it’s worth.

PS. I vote for 20k although it’s only a subjective guess.

This ^^^^^^^

I found myself thinking about this question today.

Any Japanese Natural Stone tests would have to be done with a diamond plate slurry because different Tomo Nagura raise or lower the grit level.

Generally i find that fine finishing Jnats produce too sharp an edge with a diamond plate slurry which would put the grit ratings through the roof

Not currently able to offer my opinion but I do have a 12K Naniwa on the way for comparison with my Arkies and Thuris.

Originally Posted by kelbro

Not currently able to offer my opinion but I do have a 12K Naniwa on the way for comparison with my Arkies and Thuris.

The trouble with comparing naturals is that even of the same kind there is considerable variance, not to mention that a preferred edge is fairly subjective. A 12k Naniwa should be a standard purchase for anyone getting in to honing since it at least offers a standard reference point to work from.