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.