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 ??
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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.
:shrug:
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 :D
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.
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.
Quote:
Originally Posted by Scipio
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).
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.Quote:
Originally Posted by Steve56
This ^^^^^^^Quote:
Originally Posted by Steel
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.
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.Quote:
Originally Posted by kelbro
I agree with this in principle. The problem for me is the default JIS reference that we are assuming on the forums. Only that makes a Naniwa 12k a "standard purchase" as suggested. Or why not refer to microns instead of JIS? Rather, if we go by collective wisdom or word of mouth, we might still arrive an agreed categorical system of "bevel setters," "mid-range stones," "finishers," and the like, be they natural or synthetic. At the very start, I found synth stones too aggressive. So I switched to slower-acting oil-stones like Indias and Arkansas that are difficult to rate as their "grit effect" varies as to polish and simultaneous burnishing effect. And to make matters worse, their grit ratings are given in mesh, or whatever old-school American standard it is, which throws people off. Another complication has to do with natural stones generally being more "fluid" than synthetic stones, with natural stones' effect varying more noticeably relative to added pressure and then lightening up, leading to more of a sliding-scale of perceived JIS grit-rating effect.Quote:
Originally Posted by ppetresen
Completely agree! I think we could actually pick any number of synthetic finishing hones to use as the reference point, the Naniwa 12k makes sense because of how widely adapted it already is, as well as it's relative accessibility to people. In other words, it makes sense here and now but there is nothing inherent to it that makes it a better choice than a Shapton Glass 16k (for instance).Quote:
Originally Posted by Brontosaurus
As long as people are using the same stone, we don't need to give it a grit or micron rating at all, since it would still allow people to say "In comparison to that Naniwa stone, I find the edges off this other stone keener/harsher/softer/duller/etc." This keeps the emphasis firmly on a standard starting point, one that is experiential rather than purely objective. As long as we keep this focus I don't think it matters that we're using the default JIS instead of microns, just that we're more or less using the same stone.
How do you define natural stone? Alumina is AlO2 which is just ground down to a powder. Diamond can be ground to dust and in fact is. The is no limit really with natural stones. When you say "natural" do you mean synthetic versions of these too?
By natural, I consider it formed-as-found in present time by past natural geological processes, extracted from the ground, or as found on the earth's immediate surface in the form of fallen shards, then cut or not cut to size, hopefully lapped flat, and used accordingly.Quote:
Originally Posted by thebigspendur
Understood, I hope. I can only differ in that this seems to ignore natural stones as potential references.Quote:
Originally Posted by ppetresen
A long time ago, someone gave me some advice: a Suehiro 1k/3k synth combo is great for setting things up for naturals afterwards. And in following this advice, I have to say that it has proved true from my experience. No need for any higher synth afterwards, a coticule used with water (no slurry) followed by a purple Welsh slate used with oil almost always suffices, the coticule and the Welsh purple being independent of JIS ratings.
From the perspective of synth progressions in general, it's one that I haven't used much apart from my experience with a Sigma Power 1.2k > 6k> 13k progression a few years past (or after my dabbling with a dedicated Arkansas oil-stone progression). I remember that in starting out with the said sequence, the 13k yielded a harsh or over-honed edge, which I would subsequently calm with a smoothed black hard Arkansas. It was only after continued persistence with the 13k synth as sole finisher that I realized that I was using it with too much standing water on the surface. Rather, it preferred a dampened state with no standing water, from which the end-result regarding the edge was superb. Ergo, even the use and rating of synths seems relative according to the skill, purpose, or circumstance of the user in question.
From this, I would think that certain claims for natural stones used after whatever advanced X-synth stone may be doing much the same. For example, I have never succeeded with shaving off a coticule used after a 3k synth, always needing the Welsh slate afterwards. But if I were to use a coticule to reign-in or tame a harsh edge after a Naniwa 12k, perhaps I might sing the coticule's praises in thinking it was more advanced than the 12k synth.
This topic is really not helping my headache.. I guess if anything is possible, absolute highest could be 50k + but I'd argue the stone wouldn't be homogenous at that size.
Attachment 316224
I vote 8k for naturals!
A 10k Gokumyo makes a shiny surface by comparison.
Here is a photo of a few stones, a razor, two kamisoris, a piece of 2000 abrasive paper and some oil.
I estimate my natural's grit from looking at the bevels after sharpening, with a high resolution 10x loupe. The surfaces of the bevels all look about the same to me. These are all great finishing stones and the bevels look different from the finish off synthetic stones.
I can not shave directly off any 8k stone (that includes my natural stones). It takes stropping to get a shaving edge for me.
BUT, the action, and effect, of the different stones is significant.
A synthetic 8k stone like a Chosera is very fast cutting. The scratch pattern is regular and the scratch grooves are deep. It also makes a wicked burr which does not come off with stropping, so the shave is nasty.
By contrast, my natural stones grit does not cut as deeply. The grit seems to scrape a wider, thin layer of steel off the surface. The big difference in my experience is that when using slurries with Coticules, Eschers or Jnats, the slurry seems to remove the burr as it sharpens the bevel ... but the slurry also dulls the edge. The final few laps without slurry slowly put a sharp edge on the blade, but the edge still has to be polished on a strop.
My preference is to use Arkansas stones because they are all cutting surface (no mud!) and a few drops of light mineral oil (no stink) work well for me. If I take an edge that has been prepared by a fast cutting synthetic, say 5-8k, the Ark will smooth the bevels and edge, but as there is no slurry, a burr is created too (barely visible, but it glints in the light when looking through my loupe). I remove the burr by wiping a piece of abrasive paper, very lightly, along the edge. In the photo, there is a small piece of 2k paper which I use with a drop of oil. It takes two or three wipes (very light) before the burr is completely removed so that the paper no longer grabs bits of burr. I can feel the difference. Once the burr has been removed, the edge is no longer sharp enough, so I make a few more light laps, maybe ten, to make a new edge which also has a new burr, but it is very small (insignificant).
I then polish the bevels (and edge) with the small stones shown in the photo. They are Gokumyo 10, 15, and 20k. They polish the misty bevels to a high polish quickly, also refining the edge.
This is a good edge to take to a strop. I have made a loom strop (limited sag) which I pasted with 0.25µm cBN. A few light, slow laps on the strop polish the edge to make a fantastic, durable, smooth edge for shaving.
Once I have a good edge, I seldom use a stone again. Stropping keeps the edge for a long time with a good razor. If necessary, a few light strokes on an Ark, followed by the Goks and strop take very little time or effort to restore the edge.
It makes no difference which natural stone I use. None gives me a shaving edge straight from the stone. I am really shaving off the polished edge from the strop.
I have tried some of the vitreous stones, like Jade, Jasper and agate. It looks like they polish the bevels by burnishing, but a leather strop does a better job of polishing the edge for me.
My favorite finishing stones are hard Arks, used with light oil. They are rated at about 1200 grit by Dan's, and I find there is almost no difference between the black, translucent and hard for practical purposes. They are all great.
I enjoy the variety of using other stones. I bought a really nice Jnat, from Alex Gilmore, that feels very nice when lapping. An Escher or Coticule with a thinning slurry is also very satisfying to use. The techniques are slightly different, but they all give me the roughly 8k smooth finish that polishes to a keen edge for the pleasure a smooth, painless shave.
Coticule and Thüringer: 20.000, at least.
For reference, I have shaved with a few Suehiro Gokumyo 20.000 edges, and found they were the same level of sharp and smooth as my coticule and Thüringer edges. Did not last as long, though.
Regards,
Pieter
@Cliveruss.
I'm with ya on the strop.
Something I've added to my stroppin, was to start on a linen strop coated with lead, before going to leather. This is only done, after a honing session, or touch- up.
Lead? What form of lead, and what does it do that plain linen won't do?
Hard to say, I have a couple of coti's that give a very enjoyable and durable edge I go through phases when using stones, back when I started I would finish solely on a Charney forest as that's all I had it was a dam good edge, a very good friend of mine, Hanzo who is a member on most forums but doesn't really participate anymore sadly has had many a razor from me and never complained about the way they shave,
I went from using the CF to a SG20K and now coti.
I would guess my CF to be around 16k plus
