Mamma mia!

[Halicon]

No criticisms from me and in fact other than just talk about different finishes (etc) I have nothing to say besides for a repair of this size this looks great.

We discussed the geometry and it's accuracy, not the finish. The finish is from the fingerstones, the process we had up was still while working on the stones. The manner of which I described how to establish a back is in order to make the knife last as long as possible and perform to it's full capacity. Visually things might look just fine on that knife but when it's time for the stone one will have to compensate for it all. In the end one might even end up adding harm to the knife while resharpening if the geometry and surface on the blade wasn't accurate when first restored.

Especially when the knives go out to people I know haven't practiced on the stones for a long time, having everything perfectly set up helps educate the client in how a blade should be restored and polished as well as make it easier for the user to sharpen it.

 

[Dave Martell]

Halicon, are you a professional knife sharpener or a professional sword polisher?

 

[schanop]

Schanop, If you have a king its possible to make it darker and not mirrored. But I dont have it anymore, and the effect from binsui or JNS 1K alone isnt too good lookin.

Whoopse, sorry for the misunderstanding. I was referring to the body finish, your bevel finish is nicely done I've got a hide kensaki yanagi with mirror finish, and now wish I had ordered it with the normal finish now knowing that their normal satin finish is so fine and nice. Next knife, perhaps.

 

[schanop]

This is more just for general information for people reading:
When sharpening single bevel knives, the idea is that you move the shinogi line up at the same rate you move the edge up. This maintains the geometry of the knife over time. If you want to strengthen the edge (as was done here), this can be temporarily ignored. But usually thats the way things are done. Also, the shinogi line should stay parallel to the edge (and visa versa).

Jon, could you please elaborate a little bit more about shinogi line being parallel to the edge in the case of a deba (since this is a thread about a deba)?

Most pictures that I have seen and a couple of debas passing through my hand kinda tell me that, they usually come with smaller bevel and higher angle at the heel, and slightly wider bevel and lower angle at the tip.

Even taking into account that the tip is always thinner, quite often this does not always translate -- at least visual looking straight down to the side of the knife -- into parallel shinogi line and the edge?

Hopefully, this come out right in words.

 

[Halicon]

Halicon, are you a professional knife sharpener or a professional sword polisher?

I wish I was the latter but at the point I am in my career I can't really be picky as there are still plenty of stones and tools I need in order to polish properly and match the steel of the sword to the stone.

It also seems like chefs like really sharp knives as well, who would have known?! :lol2:

To be serious however, very few, especially westerners that don't apprentice in Japan can reliably eat from polishing swords unless they are very famous and have already proved their skills to the connoiseur collectors in the world. So while I sharpen and polish pretty much anything I can reach with a stone, the sword polishing is really more of a goal of mine and a rare treat that I savor when I get the rare request to restore or polish a sword.

Strange that you bring this up here however, I don't recall mentioning that I polish swords in this kitchen knife section? Apologies if I did, it would have been quite a bit off-topic.

 

[bieniek]

The manner of which I described how to establish a back is in order to make the knife last as long as possible and perform to it's full capacity.

And how would that look like?

 

[Andrew H]

Jon, could you please elaborate a little bit more about shinogi line being parallel to the edge in the case of a deba (since this is a thread about a deba)?

Most pictures that I have seen and a couple of debas passing through my hand kinda tell me that, they usually come with smaller bevel and higher angle at the heel, and slightly wider bevel and lower angle at the tip.

Even taking into account that the tip is always thinner, quite often this does not always translate -- at least visual looking straight down to the side of the knife -- into parallel shinogi line and the edge?

Hopefully, this come out right in words.

I think what Jon is trying to say, forgive me if I misinterpreted, is that if you pick a point on the shinogi line and a corresponding point on the edge they should have the same 'slope' if you will. It's hard to explain without a picture.
What I'm trying to say is if the shinogi line is dead straight, the edge should be also. If the shinogi line has a gentle curve upwards the edge below it should have a gentle curve upwards. Someone please correct me where I'm wrong.

 

[Halicon]

And how would that look like?

Just google for ito-ura. It is in general referred mostly to woodworking tools but any hollow blade performs the best with an Ito-ura hollow. Basically it means that the contacting flat that makes the cutting edge shouldn't be thicker than a thread.

This is a Japanese plane blade but was the fastest picture of Ito-ura I could find. The left side of the back is a bit overground so the Ito-ura isn't entirely uniform but I hope it helps give you an idea of what it looks like anyway.

 

[bieniek]

yeah, if before sharpening at the heel you have from shinogi line to edge 10mm, after sharpening you should have there 10, not 9.5 or 10.5.
If on the tip area you pick a spot where there is 15 mm from shinogi to edge before sharpening, after session it should be 15.

etc

 

[bieniek]

Just google for ito-ura. It is in general referred mostly to woodworking tools but any hollow blade performs the best with an Ito-ura hollow. Basically it means that the contacting flat that makes the cutting edge shouldn't be thicker than a thread.

This is a Japanese plane blade but was the fastest picture of Ito-ura I could find. The left side of the back is a bit overground so the Ito-ura isn't entirely uniform but I hope it helps give you an idea of what it looks like anyway.

Well, OK, it wasnt thicker than a thread before chipping action.

I also found that,
http://kskdesign.com.au/blog/files/ito_ura_problems.html

And I think it only applies to a perfect ground back side. If there is any bumps or hills, the grind will look uneven.
Guess its much easier on woodworking tool, where the edge is 40mm, not 330. Or is it?

 

[Halicon]

It's actually much harder on a woodworking tool as the steel is much harder and is delivered unsharpened from the smith. What you linked to is also an issue that has been fixed by science as current planes are most often warped nowadays and not in need of Uradashi - this is quite off-topic however so I would prefer if we don't head into this area.

I don't understand quite what you mean with perfectly ground backside? Are you upset about what I have said in your thread? In no way did I mean that you should change anything to your knife, maybe your next, maybe keep it in mind or disregard it entirely. I get the feeling that you dislike my comments about your polish (which is good!) but just like with everything else there can always be improvements.

Myself I utterly destroyed the hollows of a couple of knives, Kiridashi, Kogatana, Kuri-Kogatana and numerous chisels until I was taught the proper way how to remove as little from the back as possible yet get the most out of it. You have to understand that a kitchen knife isn't smacked at with a hammer like a plane blade during the Uradashi - that is most certainly an area where such a fine edge can suffer damage but that's soft steel landing directly against the craft with force.

A hollow is established using a tool called "Sen". It is basically a piece of steel harder than the steel with a convex edge that takes small shavings out of the knife, tool or what it now might be. It isn't done by grinding as the process is too inaccurate and us sharpeners would have to remove way too much steel to get an accurate flat if that was what they used (like unsharpened traditional tools for example). After that it is up to the user and how he works with the hollow that decides what will happen to it.

Please do not worry about Ito-ura chipping for knives. Plane blades are a completely different creature and can't really be compared in that sense. The cutting action against wood stresses the serrations quite a lot more than in the case of a knife against organic material. And in the case of an Ito-ura, one simply has to place the entire back fully flat on the finisher and run it until the back is sharp again which is very welcome when you are rushed. No real pressure needed anywhere, just keep the blade flat on the stone and stabilize the tip with a finger so that it doesn't rock on the pulling stroke.

 

[TB_London]

I don't think that anyone is in any way upset with anything you are saying, we're just spread all over the world with a lot of language barriers.

l I was taught the proper way how to remove as little from the back as possible yet get the most out of it. .

It would be really interesting for you to describe the proper way that you were taught, I'm keen to learn more to improve my technique, as are others I'm sure.

 

[Halicon]

TB_London, indeed. I just had a feeling but then again that's just that and is entirely on my end.


I have a project coming up that I will try to document and show. At the moment I don't have a step-by-step guide how to do it however but hopefully in a few weeks I will. The process is very precise and require dead-flat stones, it's also especially important the way one puts pressure only on the lamination steel and not the Jigane. The pressure has to be focused very solidly there and when Ito-ura is near completion it isn't uncommon for me to shave off a layer of skin on my index finger as I put the force from the lamination and "outside the edge" - all to reduce the pressure you put on the spine while you remove material of the flat near the edge to reduce it in size.

 

[TB_London]

A step by step would be great, looking forward to it
Thanks,
Tom

 

[memorael]

TB_London, indeed. I just had a feeling but then again that's just that and is entirely on my end.


I have a project coming up that I will try to document and show. At the moment I don't have a step-by-step guide how to do it however but hopefully in a few weeks I will. The process is very precise and require dead-flat stones, it's also especially important the way one puts pressure only on the lamination steel and not the Jigane. The pressure has to be focused very solidly there and when Ito-ura is near completion it isn't uncommon for me to shave off a layer of skin on my index finger as I put the force from the lamination and "outside the edge" - all to reduce the pressure you put on the spine while you remove material of the flat near the edge to reduce it in size.

I don't think anyone here is upset at anything you have said. I for one can tell you that I am real happy you showed up, seems like your a very knowledgeable person and would really appreciate a video or WIP on how to properly sharpen a WA style knife. I have had people explain it to me a lot of times and have a sorta clue how to do it, but really I am far from being proficient. Thanks for your comments and explanations!

 

[JBroida]

A hollow is established using a tool called "Sen". It is basically a piece of steel harder than the steel with a convex edge that takes small shavings out of the knife, tool or what it now might be. It isn't done by grinding as the process is too inaccurate and us sharpeners would have to remove way too much steel to get an accurate flat if that was what they used (like unsharpened traditional tools for example). After that it is up to the user and how he works with the hollow that decides what will happen to it.

This actually isnt true for most japanese kitchen knives... two makers come to mind that do this and one of them is Iizkua-san (shigefusa). The rest use a grinding wheel.

Sharpening kitchen knives is still very different than sharpening wood working tools, kiridashi, etc. While you dont want to oversharpen the back side of these knives, some sharpening initially will strengthen the edge and improve cutting performance. Once a well sharpened ura is established, its all about maintaining that and not removing too much metal.

I made a video on uraoshi sharpening a little while back:
[video=youtube;cCY5CKkBers]http://www.youtube.com/watch?feature=player_detailpage&list=PLEBF55079F53216AB&v=cCY5CKkBers[/video]

 

[Halicon]

Jbroida, I didn't want to put it into a definitive as people here might have a hard time to accept why only some knives receive the Sen treatment and the result of it. You must have missed that all high-end woodworking tools arrive unsharpened, no harm done. Yes they are two different creatures (tempering, refining, purity etc) but the back isn't, the important thing is where you put the pressure and how you force the flat to be produced.

The ura on a properly forged and finished Japanese knife differs only in the fact that woodworking blades often arrive with the Kuroichi skin still intact to protect the hollow. Why wouldn't Uraoshi on a woodworking knife and a kitchen knife be the same by the way? They were performed with the same tool? If it was used using a grinder, well that's a direct sign of lower quality and less finish.
Take Iwasaki-san for example, he has the Sen technique down to a science and puts almost ridiculously accurate hollows on his knives, woodworking knives only though, Mizuochi-san did the kitchen knives a long time ago with the approval of Iwasaki-san.

The Sen is a very accurate tool, extremely accurate even and it doesn't produce any heat. To put things plainly, a knife that was roughly ground and have an inaccurate hollow and on top of that doesn't have very great steel and quality to begin with I wouldn't spend the hours to polish, it's simply not worth it. That's only me though, I don't have the time anymore to spend on any type of crafts and have to choose what I accept to polish.

Uraoshi literally means the meeting of the back and the front; two angles coming together, it isn't actually flattening which is what we like to call it. But the process involves mating the back with the front bevel to produce one edge instead of two which happens if they don't meet properly.

I'm getting a bit confused here because you put emphasis on that the knife and woodworking knife is different, but I was taught that when I am grinding with my upper body on a plane blade, that's Uraoshi. When I'm flattening a chisel, that's Uraoshi. Only the shape of the hollow changes and it is up to the user how he wraps his mind around that particular type of hollow in order to refine it and bring it out as properly as possible which would be Ito-ura.

 

[Schtoo]

You must have missed that all high-end woodworking tools arrive unsharpened, no harm done.

Are you sure?


Stu.

 

[JBroida]

Jbroida, I didn't want to put it into a definitive as people here might have a hard time to accept why only some knives receive the Sen treatment and the result of it. You must have missed that all high-end woodworking tools arrive unsharpened, no harm done. Yes they are two different creatures (tempering, refining, purity etc) but the back isn't, the important thing is where you put the pressure and how you force the flat to be produced.

The ura on a properly forged and finished Japanese knife differs only in the fact that woodworking blades often arrive with the Kuroichi skin still intact to protect the hollow. Why wouldn't Uraoshi on a woodworking knife and a kitchen knife be the same by the way? They were performed with the same tool? If it was used using a grinder, well that's a direct sign of lower quality and less finish.
Take Iwasaki-san for example, he has the Sen technique down to a science and puts almost ridiculously accurate hollows on his knives, woodworking knives only though, Mizuochi-san did the kitchen knives a long time ago with the approval of Iwasaki-san.

The Sen is a very accurate tool, extremely accurate even and it doesn't produce any heat. To put things plainly, a knife that was roughly ground and have an inaccurate hollow and on top of that doesn't have very great steel and quality to begin with I wouldn't spend the hours to polish, it's simply not worth it. That's only me though, I don't have the time anymore to spend on any type of crafts and have to choose what I accept to polish.

Uraoshi literally means the meeting of the back and the front; two angles coming together, it isn't actually flattening which is what we like to call it. But the process involves mating the back with the front bevel to produce one edge instead of two which happens if they don't meet properly.

I'm getting a bit confused here because you put emphasis on that the knife and woodworking knife is different, but I was taught that when I am grinding with my upper body on a plane blade, that's Uraoshi. When I'm flattening a chisel, that's Uraoshi. Only the shape of the hollow changes and it is up to the user how he wraps his mind around that particular type of hollow in order to refine it and bring it out as properly as possible which would be Ito-ura.

for what its worth, uraoshi is a combination of ura (back) and osu (to push), which described in and of itself how uraoshi sharpening is to be done. Your scope of understanding is very limited and seems like you only have an understanding of a few Sanjo based makers (one of whom is retired). Just because a few people do something one way doesnt mean everyone does or should.

Wood working tools and kitchen knives are different... even though the way uraoshi is done can be similar, the emphasis and goal may be slightly different. This is why makers of wood working tools and makers of knives choose different stones among other things.

 

[Halicon]

Pardon me if I'm being rude but you think only Iwasaki and Iizuka-san uses a Sen? Heiji is another smith that uses the Sen albeit not on the crafts geared towards the mid-end clients and where price becomes an issue.

The Sen is an old tool, a traditional tool that is used to create traditional Japanese kitchen knives, woodworking tools and even saws. For the Japanese it is a sign of high quality, that the smith took the long time it takes to use a Sen. You say that my scope is very limited - that's not the case. I believe it's your "scope" that is limited. All a Sen does is produce a more accurate hollow at the cost of more time and effort, that it is somehow only for woodworking tools or a select few is something I'm really struggling with.

To give a literal translation of Uraoshi, Ura = back. Oshi = pressure, push. The meaning of Uraoshi is in there like you say but again I fail to understand exactly where you're heading with this. The traditional way to create a hollow is with a Sen, it's the age-old method of theirs as they didn't have power tools when their swords were swung against their opponents in the warring states era.

What you bring up with using different stones for tools is also a view that is very "scoped" and limited. We like to use harder stones for tools as they are not only tempered to be much harder but also refined further than a knife and thus needs a stone that first of all cuts fast due to the harder steel but also is very accurate and doesn't wear fast as the hardness of the stone is in direct relation to the accuracy one can polish at - soft stones have a give of some 20-30 microns which makes them great for beginners as it covers mistakes to a degree. But in the case of a woodworking tool we want as little give as possible in order to have a full contact of the entire flat bevel so that we can reach the serrations at the edge evenly across the blade.

That smiths specializing in woodworking tools forges them with hard jnats in mind is almost preposterous, one can choose any stone but it's a question of the road you take to reach your goal that is the essence of jnats. Using a hard stone with the harder steel and demand for more accuracy is best solved by using a hard stone, that's as simple as it is and there's no further need to complicate things further than that.

I have to apologize but yet again I don't understand why you keep bringing this up as the Sen has been a traditional tool for hundreds of years in Japan. When doing Uraoshi on a woodworking blade, one places the entire back on the stone. When one does it on a kitchen knife, one places the entire back on the stone and push (Oshi) properly to bring the flats out and if done well you get Ito-ura.
Of course kitchen knives and woodworking tools are different but the nature of the Uraoshi isn't. One still has to think, observe and think again of how to bring the hollow out into as good of a flat as possible.

 

[Halicon]

Looking at the great names such as Usui Kengo, yep they deliver them unsharpened and therefore at 80% of the price. There are a couple of few smiths such as Tasai that like to deliver their tools semi-finished, but you also end up paying for it.

 

[mpukas]

Jon, could you please elaborate a little bit more about shinogi line being parallel to the edge in the case of a deba (since this is a thread about a deba)?

I've had conversations w/ Jon about this, and Jon, please correct me if I don't get this quite right...

What is meant by the shinogi line being parralllel to the edge means is that the bevel, hamaguri in the case of a single bevel knife, such as a deba in this case (and also applies to double bevel knives such as gyuto), will be the same width the entire length of the blade, from heel to tip. If at any point the bevel becomes wider or narrower, then the shinogi line is not parrallel to the edge. So, what does this mean? The angle of the bevel will change constantly in relation to the thickness of the knife at any given point, since there is a taper from handle to tip.

The intention behind this is that different parts of the knife are used for different tasks - the tip will have a steeper angle where the knife is thinnest, therefore sharper and more fragile, and is to be used for finer cutting such as slicing flesh. The heel will have a lower angle where the knife is thickest, therefore more robust, and can be used for more demanding tasks such as cutting through the spine of a fish to remove the head.

 

[mpukas]

This is more just for general information for people reading:
When sharpening single bevel knives, the idea is that you move the shinogi line up at the same rate you move the edge up. This maintains the geometry of the knife over time. If you want to strengthen the edge (as was done here), this can be temporarily ignored. But usually thats the way things are done. Also, the shinogi line should stay parallel to the edge (and visa versa).

Jon - I've got a question - what happens to the edge bevel on the back side as the edge gets raised closer and closer to the spine due to sharpening over time? Due to the concave back side, and keeping the edge bevel on the backside the same width, it seems to me that as the edge rises with each sharpening, the edge will move slightly to the right in relation to the center-line of the spine. Is this accurate, how is it addressed, and does it matter? Thanks much! mpp

 

[JBroida]

Jon - I've got a question - what happens to the edge bevel on the back side as the edge gets raised closer and closer to the spine due to sharpening over time? Due to the concave back side, and keeping the edge bevel on the backside the same width, it seems to me that as the edge rises with each sharpening, the edge will move slightly to the right in relation to the center-line of the spine. Is this accurate, how is it addressed, and does it matter? Thanks much! mpp

 

[bieniek]

I don't understand quite what you mean with perfectly ground backside?

I mean, the polishing there might be straight, but the surface of the concave-hollow not. It can vary in depth so to speak. What then?

Come on, im pro chef and I dont get personal about anything else than insulting women But maybe my londoner-English is "over kitcheny".

What I meant on the comment about a chisel vs kitchen knife.
Imagine, you have a chisel which is 33cm wide or even 54 [yeah] - How big of a stone would you need to put the back flat on it all at once?

Ive never seen anybody doing that on a kitchen knife. Or am I misunderstanding?

 

[JBroida]

Pardon me if I'm being rude but you think only Iwasaki and Iizuka-san uses a Sen? Heiji is another smith that uses the Sen albeit not on the crafts geared towards the mid-end clients and where price becomes an issue.

The Sen is an old tool, a traditional tool that is used to create traditional Japanese kitchen knives, woodworking tools and even saws. For the Japanese it is a sign of high quality, that the smith took the long time it takes to use a Sen. You say that my scope is very limited - that's not the case. I believe it's your "scope" that is limited. All a Sen does is produce a more accurate hollow at the cost of more time and effort, that it is somehow only for woodworking tools or a select few is something I'm really struggling with.

To give a literal translation of Uraoshi, Ura = back. Oshi = pressure, push. The meaning of Uraoshi is in there like you say but again I fail to understand exactly where you're heading with this. The traditional way to create a hollow is with a Sen, it's the age-old method of theirs as they didn't have power tools when their swords were swung against their opponents in the warring states era.

What you bring up with using different stones for tools is also a view that is very "scoped" and limited. We like to use harder stones for tools as they are not only tempered to be much harder but also refined further than a knife and thus needs a stone that first of all cuts fast due to the harder steel but also is very accurate and doesn't wear fast as the hardness of the stone is in direct relation to the accuracy one can polish at - soft stones have a give of some 20-30 microns which makes them great for beginners as it covers mistakes to a degree. But in the case of a woodworking tool we want as little give as possible in order to have a full contact of the entire flat bevel so that we can reach the serrations at the edge evenly across the blade.

That smiths specializing in woodworking tools forges them with hard jnats in mind is almost preposterous, one can choose any stone but it's a question of the road you take to reach your goal that is the essence of jnats. Using a hard stone with the harder steel and demand for more accuracy is best solved by using a hard stone, that's as simple as it is and there's no further need to complicate things further than that.

I have to apologize but yet again I don't understand why you keep bringing this up as the Sen has been a traditional tool for hundreds of years in Japan. When doing Uraoshi on a woodworking blade, one places the entire back on the stone. When one does it on a kitchen knife, one places the entire back on the stone and push (Oshi) properly to bring the flats out and if done well you get Ito-ura.
Of course kitchen knives and woodworking tools are different but the nature of the Uraoshi isn't. One still has to think, observe and think again of how to bring the hollow out into as good of a flat as possible.

there are a number of books, videos, etc. in Japan (in japanese) that agree with what i am saying... in addition, i am there every year training with the craftsmen in japan... i'm in workshops with people like Iizuka-san, Iwasaki-san, Nakaya Heiji, and a number of people in regions, such as sakai, tosa, tokyo, sanjo, ibaraki, etc. I feel very comfortable with what i have said.

FYI, Ito-Ura only refers to something desirable for Kanna (not even for nomi)

 

[mpukas]

View attachment 6486

Of course. Duh. Thnx!

 

[Schtoo]

Looking at the great names such as Usui Kengo, yep they deliver them unsharpened and therefore at 80% of the price. There are a couple of few smiths such as Tasai that like to deliver their tools semi-finished, but you also end up paying for it.

Are you really sure?

Stu.

(Finds stuff out by picking up the phone or sending an email to the folks who make the stuff. I don't know what anyone else does, but that's what I do. )

 

[Halicon]

there are a number of books, videos, etc. in Japan (in japanese) that agree with what i am saying... in addition, i am there every year training with the craftsmen in japan... i'm in workshops with people like Iizuka-san, Iwasaki-san, Nakaya Heiji, and a number of people in regions, such as sakai, tosa, tokyo, sanjo, ibaraki, etc. I feel very comfortable with what i have said.

FYI, Ito-Ura only refers to something desirable for Kanna (not even for nomi)

That's great for you JBroida.

I am in all earnest baffled that you haven't heard of Ito-ura earlier or the history of the Sen in Japan. It's good that you have solid sources such as Iwasaki-san, Iizuka-san, Heiji-san and greats like that to guide you on your way though, you're in good hands.

I also feel very comfortable with what I have said, why wouldn't either of us? It isn't a contest of who knows more or who is the best, or aren't we here to seek knowledge but instead come with ulterior motives? I won't budge on what I have written and explained and you won't budge on what you have written so I really don't see why you keep bringing this up as the both of us will only stray further off-topic the more we keep going.



@Bieniek, indeed it requires a bit of compensating from the user and usually larger stones are preferred. This whole topic is a bit sketchy to cover by writing on top of also being hard to wrapp your head around, and I'm very busy currently with a project.
I would love to demonstrate later on when I get the time though so please stay tuned.

 

[mhlee]

Are you really sure?

Stu.

(Finds stuff out by picking up the phone or sending an email to the folks who make the stuff. I don't know what anyone else does, but that's what I do. )

I always like seeing what Stu writes.