Differential grit sharpening?

[kman94]

I just watched this video from Knifewear and I found it an interesting conversation topic. I do think his "experiments" in cutting a tomato and carrot are trivial at best with no real control or measurements other than his personal feeling which is probably skewed by his bias of wanting Shibata's hypothesis to be correct. I personally also think sharpening both sides to 8k is too high anyways for general use and I often steer people away from sharpening to that grit for the exact reason that it wouldn't want to bite on a tomato, which people seem to want to be the benchmark for a sharp knife.

I think it's an interesting concept but I also wonder if sharpening one side, even if it's say 4k, over time would change the geometry of the bevel away from 50/50. I guess you could take note and switch the side that gets polished each time to prevent that. I know that one of the benefits of sharpening with natural stones is the idea that because the abrasives in the stone are different sizes/hardness, it would leave different size teeth on the edge so over time as the big teeth wear away, smaller teeth are there to keep it sharp, making for a longer edge life. But is it even significant?

To me it raises questions like, are we actually cutting tomatoes and carrots like that? Who even draw cuts to julienne? How long does that edge last compared to a standard even grit sharpening?

Let me know what you guys think!

 

[Jeff]

I think part of the reason for the Knifewear video is that by doing so many videos there is sometimes a stretch to come up with new content. Not all of the videos are for everyone, and some are just “filler.”

As for your observation concerning “toothiness” or “bite,” do you strop your edges?

Isn’t that polishing away the bite?

When I strop it makes the edge seem less sharp, but it is really just reducing the bite on the test paper I cut after sharpening.

I notice that when I don’t strop, after using the knife a few times, the edge settles in. It is like the first few onions are acting as a strop. This is much more pronounced on softer steels. Again, just my observation.

 

[Vdark]

Check out this other thread about the same topic

https://www.kitchenknifeforums.com/...fferential-grit-sharpening.61228/#post-935925

 

[Jeff]

Additional factors to add to the discussion:

1. asymmetrical grind (i.e. 70/30)

2. convex grind (or hollow grind)

3. Grantons?


Consider what the Glestain knife company does … 70/30 grind, convexed on the 70% side, double layers of grantons on the 70% side and hollowed on the back side. Relatively soft steel as well.

I know this is off-point for biting into a fruit skin, but Glestains are amazing on starchy potatoes etc. The wet sticky slices just jump off the blade.

Downside- soft ateel and complex grind does not hold edge for long and it is a difficult task to duplicate the edge when sharpening.

 

[Benuser]

https://scienceofsharp.com/2021/06/15/dual-grit-sharpening/

 

[stringer]

I started with a few thoughts but it has turned into more of an essay. Apologies.

Making adjustments to your cutting technique will have far more affect on your knife abilities than making adjustments to your sharpening technique or even changing knives. Food release, wedging, stiction, etc are all problems that can be addressed through technique without upgrading equipment.

The grind of the knife matters more than the edge bevel finish for feeling sharp, staying sharp, and food release. Chef knives for general Western cuisine food production should be as thin behind the edge as possible without incurring excessive damage from a particular use case. The actual edge finish, cutting bevel angle, or laser/workhorse status of the rest of the knife doesn't matter nearly as much as the grind of the knife near the edge in my experience.

Your bevel and grind don't have to stay constant along the entire length of the knife either. Asymmetric grinds work best with a convex face toward the part of the food that is being cut off and a flat grind toward the part of the food held in your opposite hand. I prefer my tips to have a near zero grind and my heels to have a primary cutting bevel like an axe. The beauty of freehand sharpening is that it is easy to do this and gradually shape a grind and bevel to your preferences.

All that being said what works best for me is relatively high grit, relatively firm naturals for finishing and touch ups. Hard Arkansas, antique Washita, Coticule/bbw, Llyn Idwal, Aizu, Suita, etc. I don't have problems with losing "teeth" with these stones and I feel like they impart an edge with more stability and that is more easily refreshed than a similar level of polish from a synthetic stone.

I very rarely do any sharpening beyond touchups once I have the grind and bevel of a knife dialed in the way I like. Unless there is significant damage. Fixing damage always requires thinning if you want to maintain performance. Then I drop down to sub 500 grit waterstones or India/Crystolon type oil stones.

 

[Jeff]

I started with a few thoughts but it has turned into more of an essay. Apologies.

Making adjustments to your cutting technique will have far more affect on your knife abilities than making adjustments to your sharpening technique or even changing knives. Food release, wedging, stiction, etc are all problems that can be addressed through technique without upgrading equipment.

The grind of the knife matters more than the edge bevel finish for feeling sharp, staying sharp, and food release. Chef knives for general Western cuisine food production should be as thin behind the edge as possible without incurring excessive damage from a particular use case. The actual edge finish, cutting bevel angle, or laser/workhorse status of the rest of the knife doesn't matter nearly as much as the grind of the knife near the edge in my experience.

Your bevel and grind don't have to stay constant along the entire length of the knife either. Asymmetric grinds work best with a convex face toward the part of the food that is being cut off and a flat grind toward the part of the food held in your opposite hand. I prefer my tips to have a near zero grind and my heels to have a primary cutting bevel like an axe. The beauty of freehand sharpening is that it is easy to do this and gradually shape a grind and bevel to your preferences.

All that being said what works best for me is relatively high grit, relatively firm naturals for finishing and touch ups. Hard Arkansas, antique Washita, Coticule/bbw, Llyn Idwal, Aizu, Suita, etc. I don't have problems with losing "teeth" with these stones and I feel like they impart an edge with more stability and that is more easily refreshed than a similar level of polish from a synthetic stone.

I very rarely do any sharpening beyond touchups once I have the grind and bevel of a knife dialed in the way I like. Unless there is significant damage. Fixing damage always requires thinning if you want to maintain performance. Then I drop down to sub 500 grit waterstones or India/Crystolon type oil stones.

I like your philosophy, your approach to blade configuration and how you have wxplained it.

It is an inspiration which encourages me to refine my freehand sharpening game. … I am currently a sharpening system guy.

 

[SolidSnake03]

I started with a few thoughts but it has turned into more of an essay. Apologies.

Making adjustments to your cutting technique will have far more affect on your knife abilities than making adjustments to your sharpening technique or even changing knives. Food release, wedging, stiction, etc are all problems that can be addressed through technique without upgrading equipment.

The grind of the knife matters more than the edge bevel finish for feeling sharp, staying sharp, and food release. Chef knives for general Western cuisine food production should be as thin behind the edge as possible without incurring excessive damage from a particular use case. The actual edge finish, cutting bevel angle, or laser/workhorse status of the rest of the knife doesn't matter nearly as much as the grind of the knife near the edge in my experience.

Your bevel and grind don't have to stay constant along the entire length of the knife either. Asymmetric grinds work best with a convex face toward the part of the food that is being cut off and a flat grind toward the part of the food held in your opposite hand. I prefer my tips to have a near zero grind and my heels to have a primary cutting bevel like an axe. The beauty of freehand sharpening is that it is easy to do this and gradually shape a grind and bevel to your preferences.

All that being said what works best for me is relatively high grit, relatively firm naturals for finishing and touch ups. Hard Arkansas, antique Washita, Coticule/bbw, Llyn Idwal, Aizu, Suita, etc. I don't have problems with losing "teeth" with these stones and I feel like they impart an edge with more stability and that is more easily refreshed than a similar level of polish from a synthetic stone.

I very rarely do any sharpening beyond touchups once I have the grind and bevel of a knife dialed in the way I like. Unless there is significant damage. Fixing damage always requires thinning if you want to maintain performance. Then I drop down to sub 500 grit waterstones or India/Crystolon type oil stones.

I’m finding the same thing with firmer natural stones as touch ups. Recently been using a Surgical Black Ark, Translucent Ark, Hindostan, Dragons Tongue, Washita and Coticule/BBW depending what I feel like. I give the surface a quick scrub with a broken in Atoma 140 just to get a little slurry and then quickly touch up the knife. All of these have done an amazing job on any flavor of J carbon (blue, white whatever number and AS) as well as simpler stainless like vg1, Wustoff, vg10 and aus 8.

If you haven’t tried any stones like this you totally should as it might help a good bit without getting into differential sharpening or something. Just keep your sharpening the same and try one of these. Arks especially can be picked up really cheap like soft and hard ones. Surgical black and translucent can be a good bit more but soft and hard arks are pretty cheap.

Also really all of these stones will leave plenty of bit for kitchen use. Never had a bite problem from any of these.

Further edit, Dans Whetstones is a great place to buy Arks. Bought a few from him, no complaints. You can get a wide variety of sizes and you could get like a soft and hard ark for probably $40.00-50.00 together in a smaller size

 

[M1k3]

I've definitely been preferring harder stones for edges lately. Whether that's an India, Shapton Glass/Pro, BBW/Coticule or Venev diamond.