Thread: Natural Stones Approximate Grit

What is the highest grit you think a Natural Stone can be rated at ???

Absolute highest

Yes most of us know how hard it actually is to rate them compared to a Synthetic but what do you think ??

I have a few jnats that can deliver absolutely wicked sharp edges. Keener than what I could get off a suehiro 20k easily. And that's like 1/2 micron abrasives iirc.

Glen, I voted for 10k, but who knows. We’ve been told so many times making such comparisons are unwarranted, apple / oranges. What I’ll confidently affirm is my Arkansas hard black and translucent deliver an “ultra fine,” keen edge. The Zulu Grey ain’t too shabby either. Do these natural stones deliver an edge as keen / sharp as my Shapton Glass 30k? Yes. Maybe I should change my vote.

Glen, is this a trick question after everyone telling us for years that naturals have no grit rating, lol.

I said 30k because the Gok 20k (which I have) and Shapton 30k (which I don’t have) are rated at 0.5 microns and 0.49 microns. I’ve tried a Shapton G7 that’s 0.44 micron but it was defective, it shed chunks about 200 grit, lol, so no verdict there. I have jnats that can equal the Gok fairly easily. As far as exceeding it, yes in smoothness, but maybe not a lot. So the best jnats that I have, 20-30k synth equivalent, maybe a little more if you factor in smooth.

Ive gotten 20k compareable results from a jnat. I just wish i could get it more often.

I've always been cautious not to assign JIS grit ratings to natural stones, and I don't have a lot of experience with high-grit synths. But for what it's worth, what follows is from my experience in honing razors over the past nine years. YMMV and all that. Thus far, I have succeeded in not falling down the Jnat rabbit hole as I don't use slurries and like to use oil when the occasion arises.

I go by the edge that results: does it "get me there" followed by stropping with plain leather?

The only high-grit synth that I've tried, a Sigma Power 13k, has done the trick for me. Naturals and pastes that have worked are as follows: A.J.'s Welsh purple slate (which he rates at 10k-12k); A.J.'s Welsh "Thuringian" (which he rates at 12k-15k); Vermont slate (green, mottled, and purple); Rhode Island whiteheart; black hard, true hard, and translucent Arkansas (here I think a grit equivalent is especially difficult as these stones, when polished, seem to be burnishing the edge as much as sharpening it); Charnley Forest (similar to Arkansas in effect); Solingen red crayon paste (nominally rated at 2-4 microns); and Solingen black crayon paste (nominally rated at >1 micron).

Some hones, stones, and pastes that have come close but not quite worked for me as finishers are as follows: King 8k, Naniwa SS 10k, most coticules (often nominally rated at 6k-8k), Thuris (usually considered a bit finer than a coticule), Rozsutec (an interesting sandstone nonetheless when smoothed), Water of Ayr, and the Thiers-Issard alox-diamond crayon (nominally rated at 10k). All of these hones or stones will result in a nice edge for me if followed by Solingen red- and/or black-pasted strops.

If I take the Sigma Power 13k, the King 8k, and the Naniwa 10k as my JIS references, I would infer that a natural or paste in the equivalent range of 12k-15k gets me there, whereas a natural or paste in the equivalent range of 8k-10k comes close, but not quite enough. One exception would be the red Solingen crayon, which is rated coarser but improves a coticule edge. Perhaps that's because the spine-leading pass is less aggressive? Grit ratings higher than 12k-15k don't really concern me in the same way that achromatic magnifications much above 10x are overkill in my opinion. The shave test, based on human sense and limitation, is the final arbiter.

Given the choices in the survey, none seems to consider the subsequent effect of stropping on plain leather, which, coming off a stone or hone, changes the edge's character significantly. So if I say that sharpening or honing within an equivalent range of 12k-15k gets me there, subsequent plain-leather stropping would seem to blur this distinction, rendering a nice edge off 12k or 15k regardless of the difference in sharpness between the two. And if my honing and plain stropping were really that of a virtuoso, I suppose I could blur that distinction even more, meaning that a nice edge could be obtained off hones and stones in an equivalent range of 8k-10k (i.e., great honing raises that threshold and great stropping lowers that threshold until they overlap).

P.S. After all that, I voted for 12k. Stropping takes this higher,in effect, but much above 12k seems more about microscopy than it does about shaving IMO.

I think 50k plus.

But would that be practical?

More comfortable does not always mean sharper.

I haven't got the foggiest

I would have picked 14k if that was option I voted 12K....

I have pulled of a few 16k ish plus edges but those were outliers.

I am certain I have not yet maxed out my natural stones yet. Arks, Jnat, Coti. Ask me again in about a year.