Belgian Coticule

I'm always interested in these stones as they are quite famous..

does anyone have any experience with these?

are they suitable for Japanese knives and are there similar Jnats that does a similar if not a better job than it?

The coticule is a hard and fine stone used primarily to finish straight razors. Depending on how refined you want your edge to be, there are lots of j-nats that will do about the same job, and quicker. I like suitas myself.

Thanks Rick.. that clarifies things for me if it's not really a stone for knives

Yes, I'm quite a fan of Coticules and Belgian Blue Whetstone's.... They're pretty unique stones, and whilst equally enjoyable, for me are a totally different experience than J-Nats. I'm glad that I own both.

They are very suitable for Japanese knives, and I use mine for this application all the time... In fact, I find them more suitable for abrasion resistant steels (Like Aogami, and powdered metal stainless steels.) than J-Nats typically due to the nature of their abrasive content. Japanese natural stones are silica based, but Belgian stones contain corundum garnets that are much, much harder, and can more easily shape steels with very abrasion resistant carbide structures. By building up a mud with a matching slurry stone, they have tremendous range in their cutting power, and can easily bring up an edge finished as low as 800 grit up to their final finishing range (About 6-8K approx. for Blue's, and 10-12K for the average Coticule, but some of the harder stones go up to ~15K. This is based upon scratch depths measured by straight razor enthusiasts. Feedback and speed also varies from stone to stone; just like J-Nats.) using gradual dilutions of that mud. They can even leave a very nice kasumi contrast, depending upon the stone, and like all the natural stones I have used leave toothier edges for their fineness than an equivalent synthetic... Like all stones, though, they have their own unique personalities, and preferred techniques to learn about when you get them. What you have learned with J-Nats doesn't really apply; these work very differently, so you'll have a whole new learning curve to master.

However, for steels with less resilient carbides (Shirogami, Ginsan, Sandvik SS, etc.), I really enjoy using my J-Nats, too... Different steels have different stones that they pair well with, and I am happy to have the luxury of having multiple types of stones to choose from when I sit down to sharpen. It just depends upon what you are sharpening, and what kind of experience or edge characteristic you are looking for.

Hopefully this helps...

- Steampunk

I've got a few coticules and they work fine with some finicky techniques, but I rarely use them due to their generally poorer results both in sharpening and in polishing bevels. They are better for razors, but even there I'm not a huge fan.

Steampunk seems to be wrong about a few things though, like the composition being "corundum" or the popular "grit equivalent" ratings.

I used to own about 150 coticules mostly vintage ones, in my opinion only about 10% of them where suitable for kitchen knives (means they are hard and fast enough). They where all good for straight razor honing except one that was too rough.
A good coticule beats a suita stone in the midrange work.
Blue Belgian Whetstone (not the fastest but very fine and quite hard) is good for kitchen knifes to polish after 3k synthetic stone. But will lead to a less aggressive bity edge then Chosera 5k in my opinion.

For both stones BBW and Coticule you have too deal with the slurry problematic. Heavy Slurry can be only 800-2000 Grit (about) with water only they are in the polishing stage. So if the stone releases Autoslurry of his own, even with less preassure and only a few strokes there will be never a fine result.

Greets Sebastian.

Greets Sebastian.

Yes, Coticule's abrasive content is spessartine garnet, but in this case I thought 'corundum' was a less arcane description that may be more easily recognized. Both the hardness and the shape are somewhat similar, although the actual makeup is a little different. The popular 'grit equivalent' ratings are lower, but I am going off of ratings gleaned through actual study by straight razor anoraks and my own comparisons of the stones in my collection to various synthetics under both magnification and edge testing. With very light pressure, one can achieve finer edge apexes with both BBW's and Coti's than the rated 4K & 8K equivalents that are commonly bandied.

If you do not like Coti's, this is fine; everyone has different tastes in stones (And might I say, you have some very fine taste in J-Nats based upon your posts!). However, even in the straight razor world, Coti fans and J-Nat fans are seldom the same people, and it is not for either side's sharpening superiority. They're simply different personality types, different types of skin, or different ways of using and sharpening a razor. This thread is proving to be a great example of that... Multiple people have posted with various experiences of Belgian stones, and all differ rather interestingly.

Hopefully this clarifies any confusion I apologetically may have created...

- Steampunk

Steampunk said:

Yes, Coticule's abrasive content is spessartine garnet, but in this case I thought 'corundum' was a less arcane description that may be more easily recognized.

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This is simply false. The hardness difference between corundum and spessartine garnet is pretty massive and the two are not comparable.

It is not my intent to be a debunker so I'll not annoy with a point by point response. Sorry to sound belligerent.

Not at all... My geology knowledge is second hand, and I appreciate your response.

- Steampunk

Back to topic, i forgot to mention that i don`t think a average coticule can beat a good Jnat (especially Suita Strata) for honing kitchen knives, cause Suita Stones will in most cases deliver a higher polish with more bite (microserrated edge).
I also think that a perfekt match coticule (Vintage Old Rock) with high garnet concentration will do the job faster and will leave if not maxed out (water only) a more bity edge! then a Jnat.

My sharpening progression for very good kitchen knives ends usally at Chosera 5k. Plenty of bite and sharp enough for all tasks in western kitchen, and a better edge retention then maybe 10k Synth. stones. I call me a pro honer, do this in professional environment since about 16 years now, learned much, tested hundrets of stones (all kind of known naturals, Sigma Select, Chosera, Superstones, Bester etc......) and came to conclusion that Chosera 5k works best for my harder steel knives (Shirogami, Aogami, 1.2442, 1.2562, 51200, Niobsteel customs etc.). Now i have tested high end polished Bevels done by russian custom sharpening systems and the edge retention beats my handsharpening technique quite a bit(with the same knives btw.). If i would try to use a maybe chosera 10k finish i can cut tomatoes only after a half working day, with this perfect angled systems i can cut 2 times more!

So not the stone, your technique will lead to the best result.

Greets Sebastian.

XooMG said:

This is simply false. The hardness difference between corundum and spessartine garnet is pretty massive and the two are not comparable.

It is not my intent to be a debunker so I'll not annoy with a point by point response. Sorry to sound belligerent.

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Yes, but the difference between silica and garnet is pretty wide too. I have a blue I keep by the sink for quick touch ups on my knives. Works great as a splash and go stone. I've talked the people that quarry these stones and they told me the only difference between the blue and cream stones is the amount of garnet crystals in the aggregate. No difference in hardness or fineness.

Noodle Soup said:

Yes, but the difference between silica and garnet is pretty wide too.

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That is surprising since they are in the same neighborhood on the Mohs scale at least.

The Mohs scale doesn't have even steps up in hardness. You would have to ask a geologist why that is but the difference between 9 (carborundum) and 10 (diamond) is way more than between 8 and 9.

Anyone know of a natural carborundum stone? All I can think of are man made using the mineral as a base abrasive.

(self censored to avoid trouble)

I agree, garnet isn't a 9. Ruby and sapphire are forms of carborundum that do run 9 on the scale. What I have noticed is there seems to be some disagreement where garnet falls in relation to silica. Not sure why but some charts rate it a fair bit harder than quartz, some don't.

Here are my kitchenknive Cotis:

All of them are vintage, natural grown or glued to BBB. All fit my recommends on a good natural stone for kichten knives, hard and fast.



Greets Sebastian.

If I remember correctly, the Mohs scale is relative hardness, basically "what scratches what", developed empirically long before modern scientific methods of relative hardness were around. It's not linear, it's abrasion testing.

There are several forms of garnet, as it's a complex aluminum silicate with other metals if, again, I remember correctly, and is also found in several crystalline forms even with the same general chemical formula. Some are spheriod particles, some are more angular, and deposits of "worn" garnet will be different that transformed in place garnet. Just like silicate stone, in fact -- there are plenty of fairly hard sandstones that are essentially useless as sharpening stones because all the silica particles are extensively tumbled like beach sand and don't have sharp corners. Harder than steel but round edged means very slow cutting.

One of the advantages of garnet stones like cotis is the polishing that results from fine, roundish garnet in a hard matrix. Using a stone like that produces a very polished edge with shallow, wide "scratches" - very very physically sharp and for razors, an edge that doesn't "plow" through skin cells, making for a very smooth shave and a long lasting edge. Kitchen knives don't require an edge like that, and usually perform better with some sawtooth character to cut skins and fibrous things like meat more easily.

Slow cutting stones require more skill to get a good edge as it takes much longer (more passes) to get the desired condition on the apex, and that requires the ability to hold a given angle very closely for a longer time. I'm still too wobbly unless I use a fixture (as I do for plane blades and chisels), even a slight wobble will dub back the edge very quickly.

If you have the skill set and patience, there is no reason not to use cotis on knives if they give you the edge you want. Just like other natural stones, they vary quite a bit and it can be expensive to find the right one for you....

Peter

I have been using coticules to sharpen knives for a long time, I find no problem doing so and the edge off them is extraordinary IMO. I work as a chef and do a whole lot of cutting and trust me, coticule edges last a long time, deliver a very fine edge and are just plain awesome. Most people here recommend things and don't even test their edges in a proper kitchen. Shaving nuts (which I am one also) care about knocking off beard and having a smooth shave, not the same as cutting a ton of veggies, meat and whatnot.

memorael said:

I have been using coticules to sharpen knives for a long time, I find no problem doing so and the edge off them is extraordinary IMO. I work as a chef and do a whole lot of cutting and trust me, coticule edges last a long time, deliver a very fine edge and are just plain awesome. Most people here recommend things and don't even test their edges in a proper kitchen. Shaving nuts (which I am one also) care about knocking off beard and having a smooth shave, not the same as cutting a ton of veggies, meat and whatnot.

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Well said! I like coti edges not only in my face, i love (guess had to be the right one) for touchups in pro kitchen very much.
This stones are underestimated.

greets Sebastian.

Sharpchef said:

Well said! I like coti edges not only in my face, i love (guess had to be the right one) for touchups in pro kitchen very much.
This stones are underestimated.

greets Sebastian.

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yeah, I find cotis are awesome for some INOX steels, my suisin INOX loves edges of a Coti, I do however have to stipulate that the softer cotis are the ones I like for edges on knives, kinda like the one you have with magnesium spots. The glassy ones with vein looking things aren't to my liking for knives but awesome for straights.

I was just gifted a Belgian whetstone from my German neighbour who inherited it from his dad. The stone is over 65 yrs old. The dad used it for finishing up his knives. Not sure what to do with it, but it will be in the stone box for now.

You have a nice neighbour!

Mine wouldn't even let me use his rubbish bin the day before collection.

I use my Coticules and Belgian Blues for everything and find that they can sharpen or maintain every kind of steel I throw at them, from O1 camping knives and old Sheffield straight razors to AO Super Japanese kitchen knives. Learning to use the slurry is the trickiest part, and they often behave slowly, but everything they touch gets and stays sharp.

Is there another source to find cotis and BBs other than ardennes-coticule.de? Does anyone know how the quality is from ardennes? Thanks.

Smashmasta said:

Is there another source to find cotis and BBs other than ardennes-coticule.de? Does anyone know how the quality is from ardennes? Thanks.

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Ardennes is the only mine left extracting Coticules, and they are good to deal with directly; it is a family business... However, if you want to buy Ardennes stones from elsewhere, dealers like The Superior Shave in the US (For example...) give you local options.

- Steampunk

Steampunk said:

Ardennes is the only mine left extracting Coticules, and they are good to deal with directly; it is a family business... However, if you want to buy Ardennes stones from elsewhere, dealers like The Superior Shave in the US (For example...) give you local options.

- Steampunk

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I can certainly make sure with them via email on Monday, but do you know if any of their stones are soft enough for knives, or are they all too hard and for razors? Thanks.

Smashmasta said:

I can certainly make sure with them via email on Monday, but do you know if any of their stones are soft enough for knives, or are they all too hard and for razors? Thanks.

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It depends upon what kind of fineness, and edge characteristic you are looking for... Would you finish your knives on a J-nat finer than one of Maksim's Aiiwatani's, or on a synthetic stone in the 8-15K range [depending upon brand], or a 1-micron diamond or CBN pasted strop? None are really directly comparable in the edges they create with each other or with a Coticule, but this is the kind of range where the really good Coti's max-out. If you want that level of refinement, then Coti's are for you.

If you would instead finish your knives on a J-nat slightly coarser than an Aiiwatani, or on synthetic stone in the ~6K range, than I would check out a Belgian Blue instead of a Coticule.

Also, both behave very differently than J-nats, so it would probably be advisable to read about the different veins and how Coticules work in the article linked on Ardennes website or on the Belgian stone user forum: Coticule.be . These are not J-nats, so if you are looking for a stone that cuts fast, is easy to use, and leaves a crisp edge, a stone simply being soft isn't necessarily going to give you the characteristics you are looking for.

When you talk with Ardennes, just say that you want a stone that is a fast cutter for use on knives with hard steels, and specify whether you want a BBW or a Coti depending upon your edge preference. Since you are new to these stones, this will at least give you an effective point to start learning about the stones, and what kind of feel you like or may be looking for in the future. There are some variances in feel and performance from stone to stone, even within the same vein, as has been said by others. Like with anything else, Belgian stones are a deep rabbit hole to fall down.

Hopefully this helps...

- Steampunk

Steampunk said:

It depends upon what kind of fineness, and edge characteristic you are looking for... Would you finish your knives on a J-nat finer than one of Maksim's Aiiwatani's, or on a synthetic stone in the 8-15K range [depending upon brand], or a 1-micron diamond or CBN pasted strop? None are really directly comparable in the edges they create with each other or with a Coticule, but this is the kind of range where the really good Coti's max-out. If you want that level of refinement, then Coti's are for you.

If you would instead finish your knives on a J-nat slightly coarser than an Aiiwatani, or on synthetic stone in the ~6K range, than I would check out a Belgian Blue instead of a Coticule.

Also, both behave very differently than J-nats, so it would probably be advisable to read about the different veins and how Coticules work in the article linked on Ardennes website or on the Belgian stone user forum: Coticule.be . These are not J-nats, so if you are looking for a stone that cuts fast, is easy to use, and leaves a crisp edge, a stone simply being soft isn't necessarily going to give you the characteristics you are looking for.

When you talk with Ardennes, just say that you want a stone that is a fast cutter for use on knives with hard steels, and specify whether you want a BBW or a Coti depending upon your edge preference. Since you are new to these stones, this will at least give you an effective point to start learning about the stones, and what kind of feel you like or may be looking for in the future. There are some variances in feel and performance from stone to stone, even within the same vein, as has been said by others. Like with anything else, Belgian stones are a deep rabbit hole to fall down.

Hopefully this helps...

- Steampunk

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Thanks again, Steampunk.
I rarely ever go beyond 8K synthetic or my okudo suita 4.5. I sometimes put microbevels on with Maxims shoubu asagi 5+.
Sounds like a coti might be for a later time, but I'll talk to Ardennes to see what they suggest. Also that article they have is looooong haha.

Smashmasta said:

Thanks again, Steampunk.
I rarely ever go beyond 8K synthetic or my okudo suita 4.5. I sometimes put microbevels on with Maxims shoubu asagi 5+.
Sounds like a coti might be for a later time, but I'll talk to Ardennes to see what they suggest. Also that article they have is looooong haha.

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You might actually like a Coticule edge, if that is typically how you finish. I've never used a Shoubu Asagi, but I would imagine this at least every bit as fine as a Coticule. I typically finish a bit coarser than you on most of my knives, so I tend to like BBW's... Different steels take different levels of toothiness off of a stone, as well; VG10 still has some aggression off of my La Verte, whilst Ginsan gets really smooth and almost slippery on it. Aogami gets bitier on these stones than Shirogami, in my experience. Depends upon what you are working on. Different Belgian stones also feel better on different steels I own. I like my La Veinette the better on PM steels, and my La Verte a little more on hard carbon.

The article is worth reading.

Anytime you have Belgian stone questions, feel free to ask.

- Steampunk