D. Martell Wide Bevel Sharpening

I've often been asked why wide bevel sharpening is so expensive. I think this will help to show why.

The shiny sections are from a flat diamond plate. The dark sections on the bevel show how the bevel is hollow ground with deep grooves remaining from the water wheel used during production.

In my experience I've seen this same thing on many other makers' knives. The cheaper the price the worse the issue seems to be although some maker's get good money regardless so we can't use price point as an indication of an issue or not.

Is this a problem? No not really. It's only a problem to the person who wants to thin the edge AND have it look decent afterwards.

Dave , in that case would you try to thin the blade the to get rid of those high and low spots ? Or worry about the bevel and then polish it to make it look even?


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chefcomesback said:

Dave , in that case would you try to thin the blade the to get rid of those high and low spots ? Or worry about the bevel and then polish it to make it look even?

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We have the choice of either just sharpening at the little edge bevel or hitting the whole larger wide bevel on the stones. If we chose to hit the wide bevel to thin and/or make for flatter bevels or whatever we then have to decide to either leave the mess from the maker or keep on trucking with a flatten/thin of the bevel or maybe spread the work out and do the big work over several sharpening sessions. In my case I'm usually working on a customer's knife so once I go to the wide bevel I'm committed to seeing it through to the end. The difference between hitting just the edge bevel vs doing the whole wide bevel is usually many hours of work.

Here's the opposite side of the knife. It shows the bevel as flattened out. This side was in the same condition as the picture above shows. Stones used to fix the bevel were the ATOMA 140 diamond plate and the Beston 500x.

And that knife was probably pretty thin to begin with...yikes, I bet it screams now.

Dave,

When you flatten the bevels are you not altering the intended geometry of the knife? How does the knife cut before and after with that hollow removed? I'm still trying to wrap my head around kitchen knife geometry and so I am a bit confused.

Thanks,

Pete

Good question. Also I wonder whether the geometry magic happens higher up the blade?

Pete, I think it's tempting to claim that one might lose some food release, but under almost all circumstances the variation in geometry is subtle and shallow enough (unless there is an intentional compound grind which is usually much deeper) that it likely has no real effect on food. Near-edge convexity, bevel polish, and the primary shinogi are much stronger influences on sticking, in my opinion. Raising the shinogi too much can affect things by reducing its angle (allowing food to slide over more easily) and increasing surface area that contacts the food directly. Otherwise, I doubt flattening (and some convexing if applicable) are in any way harmful to the cutting ability of the knife.

Further, knife geometry can be wildly inconsistent even from the same maker, such as the Carter shown. This is usually not extremely nuanced stuff.

Rami, most knives like this operate on relatively simple geometry, unless we talk about convexing near the edge. There are some knives that implement a hollow (accidentally or intentionally) on the hira (flat, above the shinogi) but most don't.

The Carter that Dave posted is pretty crazy. I've got two and their bevels aren't anywhere near as horrific. My Toshihiro actually was quite nice to flatten and thin; even from 800-grit, there were almost no wobbles or high/low spots. Though I like my Zakuri knives a lot...some of them have been quite a bear to achieve a nice flat even bevel on.

Carter:


Toshihiro (bottom knife):


Zakuri fresh (top knife):


Zakuri cleaned:



For the trouble that some of these cause...once the bevel has been flattened and thinned appropriately, they are some of the nicest knives out there. It's a shame more makers don't invest more time and effort in getting a consistent bevel (though it can be argued that it's not necessary as long as long as the edge itself is not affected).

Pete, I'm in agreement with Robert (XooMG) on this. That is that the knives are a lot better once the blade road (wide bevel) has been flattened out. They sure are easier to maintain and they look better too.

The food separation seems to happen up higher on the blade anyway so removing the hollow doesn't appear to be a negative on that factor and IMO stiction isn't a problem so long as the surface is made smooth vs rough (course).

This is all general in nature though, each knife can be specific in it's needs.

Robert, nice work on those bevels. :thumbsup:

Cheers, Dave. I left a little more meat on the Carter than I should have, so it'll get some more love later.

I tried for a while to hit these things with an 800-ish contrasy kasumi finish, but never liked the draggy feeling when cutting, so I've been polishing them to be much more shiny where food slides up to the shinogi and pops off more easily. Downside is that scratches show up like crazy in photos, even when they're not so bad in reality (I'm not being perfectionist).

I'm not a polisher and have limited patience so my work isn't high-level...but I just really like tall-bevel knives when they're set up reasonably well, so I thought I'd contribute.

Thanks for taking the time to answer my question guys! P.S. Beautiful work on those knives!

I couldn't agree more, Dave. Even if the concave blade roads gave an advantage, the inability to maintain makes it a liability.

Here's the before and after together.....

Nice. In my opinion the blade's not finished until the bevel is at least mostly flat. With some like my Zakuri, I don't mind spending $30-50 for an unfinished knife...but if I'm spending a few hundred and the maker expects me or a pro to spend hours finishing it, I'm not so enthusiastic. Why even glue a handle on? Just throw the whole thing together in a Ziploc bag and let the customer do it at home.

I'm currently faced with the same "problem"; ie. kasumi-looking 800 or higher grit. Just out of curiosity, what was the final pass on your Zakuri pictured, and dos it "grip" less in onions for example? (the only thing that the 800 finish seem a bit grabby on). Also, kudos on the work done. They are nice cutters, aren't they?

gregg said:

I'm currently faced with the same "problem"; ie. kasumi-looking 800 or higher grit. Just out of curiosity, what was the final pass on your Zakuri pictured, and dos it "grip" less in onions for example? (the only thing that the 800 finish seem a bit grabby on). Also, kudos on the work done. They are nice cutters, aren't they?

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Honestly, I use the 800 grit JNS because I like its consistency overall, but hate the finish. Contrasty and cool, but awful drag in food. After the 800, I sometimes switch to a muddy synthetic red aoto, which produces a finer but less consistent (for me) kasumi, which I still don't like. I've tried following stones up from there but prefer abrasive sheets. I can use a lot of different stuff but lately have ben enjoying cloth-backed 240/400-grit, then paper-backed 800/1200 on a softer substrate. I sometimes then use lapping films from 12-micron to 3-micron, but they tend to be a bit on the hard side and leave deeper scratches on the cladding, so I move to soft-backed micromesh and some cloth loaded with finer-grit stone slurry. I might even rub some autosol or whatever on just to see if I can get a little more shine.

Honestly though I don't think any specific method works perfectly. I think the Zakuri has some lower-level scratches but I polished it up to 3-micron film, then 4k-8k micromesh (dish soap and water as lubricant). Yes, it cuts with much much less resistance than the 800-grit finish, and less stickage as well; but even with visible scratches, I like a semi-mirror or mirror bevel more than misty finishes for cutting.

Don't want to hijack Dave's thread though...I'm no expert on knife polishing and don't want to mislead, so take it all with a grain of silicon carbide.

XooMG said:

Don't want to hijack Dave's thread though...

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The discussion is all good my friend. :thumbsup:

OK, as long as the sidetrack is cool, I'm now a bit confused on the kasumi finish as I always thought of it as the finish on the blade face of certain iron clad knives above the shinogi line¿ This is usually achieved through the use of finger stones from Maxim

Agreed that below the shinogi should be polished.

Is my thought process off? It is still early in the week.

Thanks

I don't know what the term "kasumi" finish technically means but to me I've always seen it as the contrasting appearance between the jigane (softer cladding - ie. iron or mild steel) and the hagane (hard steel core) that is brought out, or made to stand out, by the use of specific stones and /or techniques. Some stones will react in contrast to each of these steels making the core steel shine while the cladding haze. Finding the correct stones for a specific look on a specific knife is the challenge.

Dave Martell said:

I don't know what the term "kasumi" finish technically means but to me I've always seen it as the contrasting appearance between the jigane (softer cladding - ie. iron or mild steel) and the hagane (hard steel core) that is brought out, or made to stand out, by the use of specific stones and /or techniques. Some stones will react in contrast to each of these steels making the core steel shine while the cladding haze. Finding the correct stones for a specific look on a specific knife is the challenge.

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It literally translates to mist... But there are a few other terms that can be used to describe that kind of finish. Where it gets tricky is that in many places in Japan, kasumi also is used to indicate quality level.

In terms of the finish, it's usually from the shinogi line down when we discuss it. It most often refers to the contrast given to the hagane and jigane by the darkening of the jigane.

Thanks Jon

Dave Martell said:

Thanks Jon

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+1 Thanks!

The more I know, the less I know.

I am most familiar with the term as a general category of finish on knives for sale. They all seem to be soft iron clad knives.

Thanks again!

It's easy to get confused when the word is used for a few different things. My use is the general visual analogy, which in steel will typically be a random pattern of short scratches that scatter light, or a similar effect produced by dimples or pits from blasting or etching or other methods.

Originally Posted by gregg
I'm currently faced with the same "problem"; ie. kasumi-looking 800 or higher grit. Just out of curiosity, what was the final pass on your Zakuri pictured, and dos it "grip" less in onions for example? (the only thing that the 800 finish seem a bit grabby on). Also, kudos on the work done. They are nice cutters, aren't they?



Honestly, I use the 800 grit JNS because I like its consistency overall, but hate the finish. Contrasty and cool, but awful drag in food. After the 800, I sometimes switch to a muddy synthetic red aoto, which produces a finer but less consistent (for me) kasumi, which I still don't like. I've tried following stones up from there but prefer abrasive sheets. I can use a lot of different stuff but lately have ben enjoying cloth-backed 240/400-grit, then paper-backed 800/1200 on a softer substrate. I sometimes then use lapping films from 12-micron to 3-micron, but they tend to be a bit on the hard side and leave deeper scratches on the cladding, so I move to soft-backed micromesh and some cloth loaded with finer-grit stone slurry. I might even rub some autosol or whatever on just to see if I can get a little more shine.

Honestly though I don't think any specific method works perfectly. I think the Zakuri has some lower-level scratches but I polished it up to 3-micron film, then 4k-8k micromesh (dish soap and water as lubricant). Yes, it cuts with much much less resistance than the 800-grit finish, and less stickage as well; but even with visible scratches, I like a semi-mirror or mirror bevel more than misty finishes for cutting.

Don't want to hijack Dave's thread though...I'm no expert on knife polishing and don't want to mislead, so take it all with a grain of silicon carbide.









Great, (and very detailed!) reply. I love the matte look of soft 800 grit, but doing horizontals on onions for brunoise kinda makes me want to polish it up again, even though I don't like the "hard" shine I get with my synthetics. (sigh!). What are the sheet manufacturers you like, 3M?

Sorry about missing the "post with quote button!:O

The 800 goes a bit too dark, though it looks cool at first. It's also too coarse in my opinion for nice movement through food. Moving up to a synth aoto reduces the contrast and drag a bit but retains some of the fogginess, and I've got some natural stone stuff that can progress it further, though it takes a bit of work for me to get anything consistent straight off the stones without fingerstone polishing, and I still prefer a polished kireba over a foggy one anyway (I'm a heretic). I'd almost rather just etch or bead blast....

For paper, I've heard that you get what you pay for but I live in Taiwan and sometimes use cheap local stuff and it seems to work fine for most things. My polishing films I've got are 3M I believe, but just about any decent brand of aluminium oxide film should work. Micromesh is from an unknown source and I'm not sure I even trust the numbers on them.

Lapping film may work fine with knives--I've got some and can't bring myself to put a knife blade on it. It puts an evil (read as sharp but too agressive) edge on a straight razor so I only used it a few times and went back to naturals.

I still like the look finger stones give the blade face, I just think it's funny that I've been using them on the wrong part of the blade

Cheers

CC, You've got to hold it by the wooden end, sharpen the shiny end. How many times.....:groucho:

XooMG said:

The 800 goes a bit too dark, though it looks cool at first. It's also too coarse in my opinion for nice movement through food. Moving up to a synth aoto reduces the contrast and drag a bit but retains some of the fogginess, and I've got some natural stone stuff that can progress it further, though it takes a bit of work for me to get anything consistent straight off the stones without fingerstone polishing, and I still prefer a polished kireba over a foggy one anyway (I'm a heretic). I'd almost rather just etch or bead blast....

For paper, I've heard that you get what you pay for but I live in Taiwan and sometimes use cheap local stuff and it seems to work fine for most things. My polishing films I've got are 3M I believe, but just about any decent brand of aluminium oxide film should work. Micromesh is from an unknown source and I'm not sure I even trust the numbers on them.

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Thanks. It looks like I'll be staying with "too shiny" 'til I can afford a nice natural finishing stone!