Old Rock Coticule vs La Veinette

[SliceOfLife]

Hard stone with big (especially) garnets might not abrade the surrounding material as fast... letting you keep using the shallow exposed edges of the big garnets to get a sharp and smooth edge. Soft stone, no go with that... best you can do is running water honing... and that's still not going to replicate how a hard stone works.

So... saying a hard coticule doesn't finish finer is kind of... selective logic... I mean sure you can MAKE them behave as coarse as a softer stone... but in reality; a harder coticule with all other elements (garnet size/density/distribution) similar will finish finer, and will certainly finish finer if you're not willing to jump through hoops.

What "Hard stones aren't finer" logic makes sense as is "A coticule isn't implicitly unusually fine just because it's hard nor is a soft one implicitly unusually coarse". It's similar to how Yellow Green Thuri's aren't necessarily softer than dark blues... but there is definitely a tendency towards that. So "Yellow Green Thuris are soft" isn't a correct statement... but it's also not entirely accurate to dissuade people from assuming a YG is perhaps more likely to be soft vs a darker Thuri... Similarly... it's incorrect (in my experience) to tell someone that a harder coticule is not more likely to finish to a higher level of sharpness than a softer one.

Now this speaks for Vintages... In Modern coticules... I think it depends much more on the exact material Ardennes has been pulling lately. Are they pulling a lot of nice Hybrids and not much else of note? Hard stones are gonna be finer. A lot of soft-leaning La Veins? Might be less noticeable.

Buying Vintage Coti's though? If you gave me the choice of the harder stone or softer one. 100% of the time I want the harder one.

 

[Gamma]

I have always found harder coticules to be better for me across the board. No auto slurrying, and easier to finish to a keener edge. Less 'mellow' - but still with a Coti fingerprint.
Routinely, softer Cotis impart more of the 'mellow' experience into the equation.

Given the exact same PSD in two stones, one hard and one soft, I would expect the harder Coti to be more capable of producing a finer edge.
Not everyone wants that though. Some people will prefer a softer more mellow edge. I remember people going nuts for LGB stones back 8-9 years ago. Meanwhile, I was looking for harder Dressante stones. And so it goes.

At the end of the day, vintage or modern, I am gunning for a harder stone - always.

 

[ArtVandelay123]

That’s indeed all about de gustibus and all that.

Also what’s in the name fine?

Bart and the Ardennes folks both clearly said hardness and fineness aren’t correlated in a garnet based stone like a Coticule. It was clearly mentioned harder stones don’t mean finer stones, per se.

I’m not going to distinguish soft or hard anymore, as I cant tell how hard or soft my stones really are.
Fine for me means mellow.
Fine to other means sharp.

After some research my most mellow edges aren’t soft stones at all, my mistake.
And some of my softer stones weren’t that mellow.

Scratch the hard/soft theory in coticules. Auto-slurry, yes, that matters. Also how the slurry acts on different stones matters.

In the forums, occasionally the relationship between fineness and density (g/cm3) is discussed.
Unfortunately, there is no relationship. The fineness is determined by the size of the garnets and not by the hardness of the matrix.

Good example, look at the hardness of la verte, relatively soft, but no auto slurry!

Etc etc.
Mentioning hardness/softness and correlating that to the fineness of a stone is a futile discussion in a garnet based stone as uniquely as the coticule.

 

[JPO]

I have two newly mined La Veinette stones. One is what i would consider soft, while the other one is harder. The soft one will release more garnets then the hard one. From what i can tell the particle size is just as fine in both stones. In my hands the harder stone will produce a sharper edge then the soft one. I do not think this has anything to do with the released garnets from the soft stone, because i can get a good shaving edge off the harder stone with some light slurry on the stone. So, in this particular case the main difference is the hardness.
I have not quite figured out why some coticules seem to leave more rounding at the apex (slurry rounding) then others. I have always though the speed of the stone was important with respect to this. If the stone is fast enough to make up for the damage caused by the slurry, less apex rounding will be left after you finish.

I just wish there was a better grading system for these stones. Approximate fineness and hardness would be important metrics.
If i had the choice between a hard LV and a softer LV, i would get the hard stone.

 

[ArtVandelay123]

I just wish there was a better grading system for these stones.

It's just a very hard to impossible feat for Coticules.

Hard stones are gonna be finer.

I know many on the cyberwebz think this, but I don't follow the logic of harder Coticules are finer.

Talking and discussing with many folks irl that have extensively tested and studied many different Coticules and with the people from Ardennes, I have to disagree.

Coticules can have a slurry that loses its cut and becomes duller therefore refreshing is needed, that I most definitely agree on.

Btdubs, how do y'all test the hardness of your stone when you've concluded your finer stones are "harder" Coticules? And where do they rank?
These stones vary in hardness between a scratch resistance of 800 grams to >3000 grams, and in garnets between 5-50%, a big variance. Just wondering.


Another thing we once discussed:

If you find your edge too harsh, refinish with a few light laps on a hint of slurry. I would start with 5. You can always add more later. This should dial back your edge to a better comfort level. It's what I do with the edges for a friend with extremely sensitive skin.

Maybe in reality we are indeed more talking about the amount of auto-slurry of a stone and how that slurry has an impact on the edge when we're classifying some stones as soft and not delivering the sharpest edge possible, but an edge that's a bit dialled back; where in reality the auto-slurry doesn't really say much about the hardness of the stone but just how the garnets work on that stone.

Which would make sense, since many find the La Verte a superior finisher, yet it's generally a very dense albeit a softer stone in comparison, which doesn't easily release any slurry or experience slurry dulling.

It's also the reason why "hard" stones aren't always slow, it really turns out way more complicated that that.
How fresh garnets are released by the stone is one of the major factors that introduces differences in Coticules, it determines the speed but also the "slurry-dulling" effect.

 

[David]

At the end of the day, vintage or modern, I am gunning for a harder stone - always.

Same here. I kept a few softer LD’s that give great edges, but much prefer the harder, glassy stones.

 

[SliceOfLife]

It's not so much with refreshing slurry in my use. I don't typically slurry my coticules. Can't recall the last time I did Dilucot... and even my slowest coticules have no issues going from 8k Mesh on just water.

Hardness is evident in both feel and use. Heck even in look on the old stones (how the edges and surface wear in). To make a Gross oversimplication; as coticules move towards softness they feel more like soft slates or even sandstone, as they move towards hardness they feel more like novaculite. There are some examples that are both soft and feel a bit slick and waxy; but generally that falls apart if you add a touch more pressure and they can actually start to feel gritty. Hard stones stay in that novaculite-feeling camp even with pressure. That's talking about yellow/brown coti. Hybrids have their own character and feel in my experience that's hard to draw a direct parallel to yellow coti.

Long story short, we've all had that coticule you could scratch with your fingernail and the one you couldn't really scratch even with a pin. Not hard to tell coticules hardness differences; it runs a wide range.


I don't own or use any coticules that autoslurry in any appreciable way; and yeah that does go hand in hand with softness. Probably not 1:1, but there's enough overlap; you can talk about aggressive autoslurry and overly soft as one issue. In the same way; autoslurry and softness both would logically lean towards larger garnets... as when the garnets release; more substrate releases; creating a faster/bigger pool of slurry. But again; this won't be 1:1... more of an indicator.


Basically Coti Garnets run anywhere from ~1 micron or smaller to 25+ microns. If you've got a soft stone that's all small garnets; even heavy autoslurry won't matter... It'll act like an autoslurrying fine Jnat or Thuri... because the garnets are so small. These stones are pretty darn rare though... especially because all my collecting has indicated is that those ultra-fine garnets are FAAAAAAAAAAAAAAAAAAAR more common in harder stones and are extremely rare in the softer ones.

*Fun side note... of the three "Ultra-fine but soft" coticules I've bought (BST & eBay)... Two were PDSO's and one was a reform/synth Coti barbers hone.*

As you move towards more typical sizes... autoslurry becomes the primary worry about Soft stones. And as you move towards larger sizes; even stone hardness no longer offers guarantees; but often you can often make the stone work well with careful use... whereas with the same size garnets in a softer stone; it's a mess.


But all that said; In general? I think my preference has little to do with these practical considerations for most users and more to do with the simple fact that almost all of my finest (and smallest garnet sizes) coti's have been very very hard stones.

 

[ArtVandelay123]

But all that said; In general? I think my preference has little to do with these practical considerations for most users and more to do with the simple fact that almost all of my finest (and smallest garnet sizes) coti's have been very very hard stones.

How did you measure the garnet size?

 

[Gamma]

The harder Cotis, particularly the hardest La Verte available back then, were what I gravitated to early on. Dressante also. It was apparent that those stones were less inclined to adding additional curvature to the bevel's geometry. Producing more of a V an less of a U. The more acute geometry is the foundation of sharpness. It's not the final word but without it - relative or comparative sharpness will always be diminished.

Ten or 12 years ago, the quarry and certain Coticule poobahs kept pushing softer options as being better for razor honing. I never agreed and as a result I've spent a good bit of time being at odds with the know it alls. I remember Ardennes selling LL hybrids as being for 'tools only'. So while the 'experts' minds were in one place, I was producing sharper results on razors with harder stones.

Initially, I gauge hardness by the wear resistance to a particular diamond plate. Shale, for example is always shale and it's mohs hardness will always be in a 'zone' as a result. Jnat Awasedo, being shale, are not all the same hardness though. The deinsity of the stone factors in, how compact it is, etc. Same with Coticules. When people sharpening things speak of hardness, they aren't always only referring to mohs hardness of the stone. A whetstone lapping like hot butter on a cheese grater are soft, those that that defy a 140x diamond plate are harder. Degrees of grey fall in between. If someone needs to argue about something here they might say that hardness isn't the correct term. In reality, we know what we're talking about and semantic distractions are pointless.

Some soft stones are slow as hell, some soft stones are fast. Same for harder stones.

Harder and slower would be a preference for me but harder and faster are fine too.

The softest stones do not interest me, I don't have a place for them. If I used coticules for things other than razors, and I don't, then maybe.

If I have a harder stone and a softer stone I will always pick up the harder stone.

I base my findings and needs on my own experiences, not what others think, say or do. Like many others here, I've had countless discussions with a large number of people involved with these stones, up to an including people who own and work at the quarry. I have learned a lot from many of them, but in the course of the myriad conversations, not everything said has always been pure fact. What I have learned over the years is that what I find to be true on my bench with my stones and my razors is all that matters. If someone needs to disagree with those things, fine by me. Might as well go shout at clouds though.

I find harder Coticules to leave finer edges. Do not recall one that didn't.

I don't recall a single softer coticule leaving a keener edge than the harder examples I have owned were capable of.

Maybe sometimes when comparing edges things were close, maybe not, Maybe my honing was off, maybe not. Maybe sometimes it's just splitting hairs and not that important at the end of the day. Perhaps. initially, harder stones left sharper/keener shaving edges. Later on, looking at edges under high magnification, harder stones left less convexity, every single time. Mind you, I can hone on a harder stone and leave a convexed bevel if I want to, just takes using slurry and or pressure incorrectly. I don't need to skew results though. I leave those tactics for the confirmation bias crowd.

Just saying, in general over a ridiculously large sample size, harder coticules have proven to be more likely to help me get my edge where I want it.
Not where Bart wants it, not where the quarry wants it, not where microscope addicts want it, not where the Norton 8k crew wants it.
Where I want it.

Whether the harder stones in question are actually technically finer than any other is another discussion. To me it doesn't matter. With these stones, I rate them by what they do for me when I use them, not industrial technobabble. Even with synths, it is possible for two stones with X µm abrasive of the same exact type perform differently than each other due to binder type/density differences, along with variations in PSD. This applies to natural stones also. For example, some super hard Jnats are useless because of the ultra low abrasive content.

Preferences, honing skills, honing technique, pre-existing edge condition, steel type, etc - all that and more matters and it all factors in at some point.
If someone believes they hone better on a softer stone, fine by me, doesn't change what happens here though.

 

[ArtVandelay123]

Yinz are correct though.
With something like razor shaving it is indeed mostly a trial and error things, by experience, by feel and by personal preference, etc.
I also love the hybrid LL side, a super hard but incredibly fine stone, once regarded by the miners/owners as a defect. So that is indeed telling something.
You can scientifically do research and all that, but only one thing really matters in real life.

It's good to be reminded that statements by other folks and scientific research, etc. doesn't mean that much in per se in real life, which is the only thing that truly matters, how your real life shave feels. Not sure why I got caught up like that in the whole discussion. Woops.

 

[SliceOfLife]

Slurry under scope with a scale lense

 

[JPO]

In my experience the surface condition on these harder coticules makes a big difference, especially if they are not used with slurry.
A hard stone with large garnets can finish a razor really well if you don't have allot of fractured garnets sticking up at the surface.
I have a really hard La Grise. I noticed that it would always be problematic after lapping. As the surface settled down it got better and better.
This stone is now shaped convex. This means that I don't have to lap it. I maintain the shape of the stone with the razor and a slurry stone. This hard and coarse stone now cuts as fine as some softer stones that have finer garnets. The point is that the surface condition on these particular hard brittle stones make a big difference in how they can finish.
With all my other coticules I just lap them before i use them with no issues.
Now I am considering flattening the stone again and try to come up with a way to keep it reasonable flat, while at the same time maintain a broken in surface. The stone was able to give some of the best coticule edges, but it was a little hit or miss.

 

[Christian1212]

This stone went ~2 years without being lapped. Was busier at that time so only honed when necessary (touch up every 25 ish shaves on this stone). Touch ups were just water only until the razor felt good again. I don't think it is that hard to break in the surface on a coti though, just use a slurry stone to build up some slurry and run some steel on it. This stone does not get used as much anymore but was flattened recently.

 

[H Brad Boonshaft]

So, not a big believer in “dead flat” stones especially for softer stones like Jnats, Coticules and Slates. The razor will just ride on the high spots and the low spots do not even touch the steel.

Look at the pencil marks on one edge of your stone and even after all your honing the remaining pencil marks are untouched.

I use 140-grit diamond plates for initial flattening, I have an Atoma and $30 CKTG plate, they both work equally well.

Bottom line if you like your edges, that is all that matters. I would not waste the stone, just to get it flat.

Great looking and performing stone.

 

[JPO]

This is a newly mined La Veinnette. This was lapped flat, and have only honed two razors since it was lapped.

By only doing rolling x-strokes, and rotating the stone to get even wear, the stone wil develop a high spot, and get convex. By doing only up and down strokes without shifting the pressure it will develop a low spot in the middle.
So, especially for softer stones this might be something to consider.
With this particular stone I could maintain the shape by just honing and by dressing down the high spot with a nagura indefinitely.
People wonder how you can maintain a convex stone. The answer is simple, you just hone.

 

[ArtVandelay123]

This is a newly mined La Veinnette. This was lapped flat, and have only honed two razors since it was lapped.

By only doing rolling x-strokes, and rotating the stone to get even wear, the stone wil develop a high spot, and get convex. By doing only up and down strokes without shifting the pressure it will develop a low spot in the middle.
So, especially for softer stones this might be something to consider.
With this particular stone I could maintain the shape by just honing and by dressing down the high spot with a nagura indefinitely.
People wonder how you can maintain a convex stone. The answer is simple, you just hone.

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It's interesting though, something about how they lap the stones at Ardennes, all my stones coming from them had a bump width wise, lower at the edges and a higher in the middle.

The Coticule has been heavily used with oil over here in the past centuries, especially for razor honing, I'd think that was also to counter-act the slurry-release and slurry dulling effects? I haven't done the test of honing on oil and then looking at the convexity of the bevel in comparison to water.