Coticules

[SwampDonkey]

That is an amazing edge! I've never seen a knife cut paper towel so easily! May I ask what your deburring method is and any tips you might have?

I'm not nearly the sharpener that cotedupy is but I've found deburring on cotis to be easy with just edge leading strokes and as little pressure as you can manage. Wash off slurry and use water, just do a pass, flip sides, repeat a few times. I cut a paper towel to help show any problem areas that need a bit more touch up, and @captaincaed 's method of putting a paper towel or tissue over the blade to help feel small burrs as your run your fingernail along edge has been exceedingly helpful.

 

[hibbs00]

I'm not nearly the sharpener that cotedupy is but I've found deburring on cotis to be easy with just edge leading strokes and as little pressure as you can manage. Wash off slurry and use water, just do a pass, flip sides, repeat a few times. I cut a paper towel to help show any problem areas that need a bit more touch up, and @captaincaed 's method of putting a paper towel or tissue over the blade to help feel small burrs as your run your fingernail along edge has been exceedingly helpful.

I have a really hard time removing the burr. I can't find a method that works for me. I'm trying high angle passes. 45 degree light leading passes. Just 1 or 2 each side and then back sharpen to remove the microbevel. I'm not sure if I need to do that on the course or fine stone though. Or both. My goal is to push cut but like I said, I can't find a method to work for me yet.

 

[deltaplex]

I have a really hard time removing the burr. I can't find a method that works for me. I'm trying high angle passes. 45 degree light leading passes. Just 1 or 2 each side and then back sharpen to remove the microbevel. I'm not sure if I need to do that on the course or fine stone though. Or both. My goal is to push cut but like I said, I can't find a method to work for me yet.

I find cotis too fast for me to deburr on, I end up making a microburr most of the time. I usually grab a novaculite to deburr and refine on if I'm using a coti for raising the burr.

 

[cotedupy]

I find cotis too fast for me to deburr on, I end up making a microburr most of the time. I usually grab a novaculite to deburr and refine on if I'm using a coti for raising the burr.

I think ^this^ is an extremely shrewd and salient point with regards to natural stones that are very fast relative to their 'grit' level.

In that vid with the Mazaki; the reason I spend more than half the time 'deburring' is that the coti is so quick, that to begin with it's just flipping microburrs back and forth with every stroke. And I was still helped by the fact it's not a desperately hard example of a coticule.

When stones are very fast and very hard, it sometimes becomes almost impossible to deburr perfectly. I see the effect most prominently on a lot of Washitas and Turkish/Cretan.

 

[cotedupy]

I think ^this^ is an extremely shrewd and salient point with regards to natural stones that are very fast relative to their 'grit' level.

In that vid with the Mazaki; the reason I spend more than half the time 'deburring' is that the coti is so quick, that to begin with it's just flipping microburrs back and forth with every stroke. And I was still helped by the fact it's not a desperately hard example of a coticule.

When stones are very fast and very hard, it sometimes becomes almost impossible to deburr perfectly. I see the effect most prominently on a lot of Washitas and Turkish/Cretan.

And this same phenomenon is also the reason, I think, that some good Japanese stones work so nicely for knife edges even when they're not desperately quick...

Faster stones provide bitey-er, toothier edges. But so do softer stones. It seems to me that a lot of the best high mid-grit / nakatoishi jnats I've used kinda make up for their lack of speed by being a little bit softer than Cotis, Washies, Turkish &c. And that also makes it easier to whittle burrs down, rather than flipping them back and forth. A bit like Belgian Blue.

They might not quite hit the absolute heights of a really good Coti / Washy / Turkish edge. But they can sometimes get very nearly as good, whilst being a bit easier to use, and probably also better for polishing.

 

[captaincaed]

I have really begun to appreciate the BBW side of the combo stones for their assistance deburring the coti edge. After doing the majority of the work on the coti, the blue side is slow enough that it helps eat the burr and reveal the edge. Light pressure and a handful of strokes, and I can feel the dragging sensation decrease until the whole edge slides smoothly on the stone.

I’m curious about your experience with hardness/softness and burr formation. I don’t tend to consider hardness as a factor, but I guess I should. I think more about abrasive shape and speed.

 

[cotedupy]

I’m curious about your experience with hardness/softness and burr formation. I don’t tend to consider hardness as a factor, but I guess I should. I think more about abrasive shape and speed

As you know; everything I say is just based on personal experience, and hunch about what's going on. I'm not a looking-at-stuff-under-microscopes kinda person, and other people may have different experiences. So take it with a pinch of salt, but...

I find softer natural stones are less likely to raise noticeable burrs in the later stages of sharpening, especially if you use full-length strokes to deburr (as I do). Whether that's just because of the friability, or because a lot of the more popular softer stones are also somewhat slower than cotis/washies/turkish: I don't know.

And FWIW - it's not something I'd consider particularly noticeable on hard vs soft synths, when comparing two stones at the same grit. So it might just be one of the many mysteries of natural whetstones.

 

[tarnschaf]

Hi i just got a nice Coticule and so i started to read.
I thought i link it here
https://bosq.home.xs4all.nl/info 20m/grinding_and_honing_part_4_belgian_whetstones.pdf
Cheers

 

[Heckel7302]

Scored this old Coti for a good price on eBay

Seems like it has potential. Some manganese dots on one of the corners

I thought that the back side would be BBW, but now not so sure. Slurry from a diamond plate is dark grey, not purple like my other natural combo

It was somewhat dished so I assume it was used. Under direct sunlight there are some striations in it. They aren’t cracks

Any thoughts?

 

[Skylar303]

Scores this old Coti for a good price on eBay

View attachment 326577View attachment 326578
Seems like it has potential. Some manganese dots on one of the corners
View attachment 326580

I thought that the back side would be BBW, but now not so sure. Slurry from a diamond plate is dark grey, not purple like my other natural combo

View attachment 326582

It was somewhat dished so I assume it was used. Under direct sunlight there are some striations in it. They aren’t cracks

View attachment 326583View attachment 326584View attachment 326585

Any thoughts?

Older glued slate back, not meant for sharpening, just stability. The coticule part should be nice though.

 

[SwampDonkey]

Scores this old Coti for a good price on eBay

View attachment 326577View attachment 326578
Seems like it has potential. Some manganese dots on one of the corners
View attachment 326580

I thought that the back side would be BBW, but now not so sure. Slurry from a diamond plate is dark grey, not purple like my other natural combo

View attachment 326582

It was somewhat dished so I assume it was used. Under direct sunlight there are some striations in it. They aren’t cracks

View attachment 326583View attachment 326584View attachment 326585

Any thoughts?

Yeah that looks like my slate backings on other cotis

 

[Heckel7302]

Older glued slate back, not meant for sharpening, just stability. The coticule part should be nice though.

That’s what I figured. Kinda disappointed, but it’s always a gamble with eBay stones. It was only $70 so still feel like it’s a decent deal for a vintage 7x2” coti.

 

[captaincaed]

Yeah that's a fair price, and a good thick slab of yellow. Put it into service!

 

[M1k3]

That’s what I figured. Kinda disappointed, but it’s always a gamble with eBay stones. It was only $70 so still feel like it’s a decent deal for a vintage 7x2” coti.

If the layers are wavy or blend into each other, then it's a natural combo.
Straight line where they meet -probably- means slate backing.
There are man made versions of BBW/Coticule though.

 

[cotedupy]

If the layers are wavy or blend into each other, then it's a natural combo.
Straight line where they meet -probably- means slate backing.
There are man made versions of BBW/Coticule though.

IME glued slate backings are far less common than glued BBW backings. I don't think I've ever found a slate backed one, perhaps more common in the states than over here...?

It always struck me as a slightly odd thing to do. You have to cut through so much blue stone to get to coticule veins, I never understood why they then bothered importing slate from Portugal, or even Brazil apparently, to use for backing.

 

[Rideon66]

IME glued slate backings are far less common than glued BBW backings. I don't think I've ever found a slate backed one, perhaps more common in the states than over here...?

It always struck me as a slightly odd thing to do. You have to cut through so much blue stone to get to coticule veins, I never understood why they then bothered importing slate from Portugal, or even Brazil apparently, to use for backing.

I think the level of older used coticules over there is much higher so not that many of the newer ones floating around. Which is why most of your glued backing is BBW. The states has far less old stone floating around and probably more of the newer mined stuff.

My understanding of this is $. It was how they made the math work once they realized the BBW was a usable sharpening stone and not just for backing. They could sell on its own. I believe this was the only way they were able to make it work to reopen the mine at all financially. Since then they have found more ways to sell other scrap and rubble to help fund it too. Plus certain layers required some sort of backing that didn't come as natural combos and so if they could sell the BBW by itself it was like loosing $ to sell it as a free backing.

From the website. In order to keep the business running he had to come up with a plan to sell other products of the quarry to the industry and consumers. He discovered that the blue layers had almost the same qualities as the yellow Coticule. This is the moment he developed the Belgian Blue Whetstone.

 

[Cliff]

My recent purchases from Ardennes coti are backed with slate.

 

[cotedupy]

I think the level of older used coticules over there is much higher so not that many of the newer ones floating around. Which is why most of your glued backing is BBW. The states has far less old stone floating around and probably more of the newer mined stuff.

My understanding of this is $. It was how they made the math work once they realized the BBW was a usable sharpening stone and not just for backing. They could sell on its own. I believe this was the only way they were able to make it work to reopen the mine at all financially. Since then they have found more ways to sell other scrap and rubble to help fund it too. Plus certain layers required some sort of backing that didn't come as natural combos and so if they could sell the BBW by itself it was like loosing $ to sell it as a free backing.

From the website. In order to keep the business running he had to come up with a plan to sell other products of the quarry to the industry and consumers. He discovered that the blue layers had almost the same qualities as the yellow Coticule. This is the moment he developed the Belgian Blue Whetstone.

Ah yeah! That would certainly all make sense in terms of there being relatively few (almost no) slate-backed versions to be found here.

And I hadn't actually clocked it wasn't until Maurice that Belgian Blue actually became a thing. Interesting!

 

[Heckel7302]

IME glued slate backings are far less common than glued BBW backings. I don't think I've ever found a slate backed one, perhaps more common in the states than over here...?

It always struck me as a slightly odd thing to do. You have to cut through so much blue stone to get to coticule veins, I never understood why they then bothered importing slate from Portugal, or even Brazil apparently, to use for backing.

That was my thinking, most I’d seen had BBW backing so made an assumption.

 

[Rideon66]

Ah yeah! That would certainly all make sense in terms of there being relatively few (almost no) slate-backed versions to be found here.

And I hadn't actually clocked it wasn't until Maurice that Belgian Blue actually became a thing. Interesting!

Yeah you see a lot of old unbacked coticules out there, but you don't see Old BBW by itself really unless if fell off the Coti. It was only used for backing in those days. I mean I am sure some who had the combo tried and used the BBW, but I don't think they were ever marketed before Maurice.

 

[SwampDonkey]

Yeah I've got 3 from AC and 1 from a different vendor, all purchased "new" and have slate backings

 

[cotedupy]

That was my thinking, most I’d seen had BBW backing so made an assumption.

Well whichever way - you've got a thick amount of yellow in a very nice size there. 70 bucks looks like a complete steal. Nice find!

 

[stringer]

IME glued slate backings are far less common than glued BBW backings. I don't think I've ever found a slate backed one, perhaps more common in the states than over here...?

It always struck me as a slightly odd thing to do. You have to cut through so much blue stone to get to coticule veins, I never understood why they then bothered importing slate from Portugal, or even Brazil apparently, to use for backing.

I have never found a glued slate combo and I have had half a dozen or so glued with bbw and another half dozen natural combos. All of mine are pre 1940 probably.

 

[David]

@cotedupy what are these coticule stones that you speak of? They sound dreadful.

 

[cotedupy]

@cotedupy what are these coticule stones that you speak of? They sound dreadful.

Mmm, yes indeed! If you want something cheaper, more consistent, and at least as good - I would strongly advise checking out the blue version...

https://www.kitchenknifeforums.com/threads/belgian-blue-whetstone.59068/

 

[David]

Mmm, yes indeed! If you want something cheaper, more consistent, and at least as good - I would strongly advise checking out the blue version...

https://www.kitchenknifeforums.com/threads/belgian-blue-whetstone.59068/

Pass!

 

[David]

Here’s one I keep in the basement kitchen where I do most of my sharpening. It’s a really beefy Les Lat. The yellow side is insanely fast and leaves a great knife edge, the hybrid is like most other hybrids. One of my go to edges is shapton glass 500 to a quick session on the hybrid side of the Les Lat.

 

[David]

Here’s a video showing off the speed when I first got it. It’s not the fastest coti I’ve owned, but it’s in the conversation.

 

[Skylar303]

Here’s one I keep in the basement kitchen where I do most of my sharpening. It’s a really beefy Les Lat. The yellow side is insanely fast and leaves a great knife edge, the hybrid is like most other hybrids. One of my go to edges is shapton glass 500 to a quick session on the hybrid side of the Les Lat.
View attachment 330999View attachment 331000

Cool, looks like a little bigger version of my one I use for my in hand razor honing.

 

[David]

Here’s another one that’s super under a knife. It’s just soft enough that it almost pushes back at you while you’re honing. The feedback feels like
you’re honing on a thuri. It’s another one that leaves a really nice toothy edge that we all look for. All of the lines are tight, you can’t feel them at all.