Hardness vs sharpness and Honyaki question.

[Kowalski_Boston]

Have a couple questions. First is I keep hearing over and over again on YouTube, various forums, how better heat treatment brings knife to higher hardness which allows it to be made sharper. Now R2/G2 steel with 62-65 HRC is harder than Shirogami#2 (60-63), yet, it is Shirogami which can be made sharper. Now the question is, is this because Shirogami also has finer grain structure? Is maximum feasible sharpness function of hardness and small grain structure? Do I guessing correctly?
Second question is about Honyaki. I was told for best performance in sharpness I should seek carbon steel, because stainless steel will simply not perform. To my understanding Kasumitogi makes Carbon Hagane slightly less sharp (supposedly cladding process takes some carbon from core), while Honyaki actually slightly increases hardness of edge, where it becomes feasible to make thinner more acute angle on edge, it will be able to hold (however more brittle it will become). Fine! The question then however is: what sense in making stainless steel Honyaki (which are made quite few) since stainless steel even Honyaki will not be same sharp as simple mono steel Shirogami? Do I err or lack somewhere in my assumptions?

[Bensbites]

Hello. Are you in the Boston Mass area too?

Carbon vs stainless. Carbon knives are way way easier to heat treat. I will put properly heat treated stainless up against any carbon steel.

Stainless production knives are harder to control heat and cooling in huge batches. As a small maker who heat treats 3-10 knives stainless knives should be top performers.

[salemj]

Good questions.

Most of the information you cite lacks nuance and subtlety.

First of all, "sharpness" is a big category. To claim that a Shirogami knife can be made "sharper" than a stainless knife is to use a very particular definition of sharpness. Assuming you are talking kitchen knives here, the difference between how "sharp" a very good stainless knife can get versus how "sharp" a very good carbon knife can get is usually far more limited by the sharpener's talent than by the steel's potential. Theoretically, sharpness is defined by the apex, and theoretically, a stainless apex can match a carbon one at close to the atomic level. But practically, we know it is harder to achieve such an edge on different knives based on the steel and how it sharpens, and - again, practically - we also know that it is less about how sharp an edge can get in theory than how sharp a real, workable, durable edge can get while still being functional in the kitchen (or field).

I would agree that the hardness and grain structure (and heat treatment) DO have a major effect on the potential of a steel. Where I see a lack of nuance is to suggest these things are categorical (e.g., "carbon" and "stainless" as block categories). The potential of steels is not so categorical. There are powdered stainless and semi-stainless steels that take high hardness AND very keen edges, and there are carbon steels that are limited in how fine their grain structure is and how well they perform at higher hardness. More than this, the lack of reactivity is itself an important function of a blade. A very, very sharp blade is not very useful if it is rusting under use, staining food, or contaminating food with flavour; likewise, a stainless one isn't very functional if it can't hold an edge.

But more than all of this, the biggest difference you'll notice in the kitchen is not "sharpness" the way you use it above, but "sharpness" as functionality according to a specific purpose (the ability to sharpen, the ability to hold an edge, the durability of the edge as measured in countless ways including not just resistance to chipping, but also its "stretch," carbide structure, micro-chipping issues, abrasion qualities, etc., all while being "sharp"). This is where nuance is really, really essential. Most "edges" are limited more by these other qualities of the steel than theoretical sharpness. For example, you can theoretically get any steel to the same apex, but only steels with the appropriately hardness and durability will be able to hold that edge...and their ability to hold that edge is not "theoretical," but practical, meaning some will hold it cutting food but not rope, others rope but not wood, etc. This is one reason why arguments about "best steels" vary wildly between field knives and kitchen knives. In the vast majority of cases, the real limitation of a steel is how thinly it can be ground at the edge while remaining durable, and not how "sharp" the alloy itself can get. This is why knives with really hard steel that take very "sharp," keen edges can also chip easily, etc.—something you note yourself. But remember that being "brittle" is not just about being thin. It is about the alloy. The durability of the steel varies dramatically based on the alloy (as well as heat treatment), such that the durability of one carbon is different than another (including Hitachi "blue" steels versus "white" or shirogami ones). But durability also makes a knife harder to sharpen...even if it can get just as sharp. Shirogami 1 is easier to sharpen because it has fewer alloys, but it does not "get sharper" than Aogami 1 in any practical sense.

Your question about honyaki relates more to function than sharpness, too, in my mind. The kind of honyaki you are referring to are "differentially hardened," meaning that the spine is softer and more forgiving than the edge. The point of this is to provide a hard edge while having a more forgiving spine, NOT to be magically "sharper." [In fact, in my experience, it is hard to find carbon honyaki gyutos that are ground as thinly and get as "sharp" as easily as non-honyaki ones precisely because they are harder to grind, harder to sharpen, and may be more brittle than their non-honyaki counterparts and so they are not ground as thin at the edge, but I suspect it is easier to find single-bevel honyaki that are ground as thin or thinner than their non-honyaki counterparts.] But there are also "honyaki" that are just a single piece of steel ("mono-steel") rather than differentially hardened. Most stainless honayki are of this type, meaning they are not differentially hardened. This means they fit into a different category of use...and their "practicality" is also different. I would claim that the VAST majority of people using mono-steel stainless knives would strongly prefer then to using a carbon honyaki for specific tasks. The reason? Most differentially treated honyaki are not designed as work-horse knives for professional kitchens, while most monosteel stainless knives are. They function better in these environments, and they get PLENTY sharp for those purposes, even if they may not get as sharp under more ideal conditions.

Not sure if this helps. You clearly understand a lot of this already, but your questions also suggest it may help to take a step back and fill in a few gaps.

[Jeff B]

....better heat treatment brings knife to higher hardness which allows it to be made sharper....

False, higher hardness will usually help in edge retention but not sharpness. Higher hardness will also make a steel harder to sharpen.

...Is maximum feasible sharpness function of hardness and small grain structure?...

Finer grain structure has more to do with "sharpness" than hardness of the steel. The hardness a steel is tempered to has more to do with the balancing of edge retention, sharpenablity while keeping that specific steel stable.

...I was told for best performance in sharpness I should seek carbon steel, because stainless steel will simply not perform.

In the past this might have been true but not with modern stainless steels.

[jmcnelly85]

Two identical steels can be treated to an identical Rockwell hardness; however, they may not have the same heat treatment. Two bread loaves with identical ingredients can have identical crust, but it doesn’t mean they’ll taste the same. Rockwell hardness is only one small part of the equation. Its importance is overstated because it’s an easy number to point to, but it doesn’t necessarily mean much.

[jmcnelly85]

https://youtu.be/v8xK69vWITk?si=oOHMSDYz3W2X7-bY

[taz575]

Higher hardness (with correctly sized grain structure for the steel) will allow an edge to remain intact longer, providing there is sufficient toughness at that hardness to keep the edge from rolling or crumbling. You can get the same HRC with different heat treat recipes that has been said, but the internal structure is equally as important! A steel may be brittle with large grain at 64 HRC, or much finer grained and tougher at 64 HRC based on how it was heat treated. Higher hardness with fine grain structure may feel "sharper" because the edge is more uniform and consistent if it's not "crumbling", so some equate higher hardness with sharper feeling, unless they have an edge that wears/crumbles easily, which usually means it brittle. Harder edges often deburr better (less gummy), so it maybe easier for people to get them properly sharpened than softer/gummier steels, regardless of the carbide content.

Carbon steels (Blue and White) have a very fine grain structure to them, but not much carbide content. They take a wickedly fine edge easily, but edge retention is lesser. There are more highly alloyed carbon/tool steels that have more alloys to them which can make sharpening more difficult and the edge may not feel as sharp and the grain structure isn't quite as fine. To get better edge retention, the hardness may be bumped up instead of having carbide formers present in the steel.

Stainless steels vary a lot. Some are very fine grained (AEB-L, which also doesn't have much carbides in it), others are much coarser grained (D2, VG-10) typically, but have carbides for better wear resistance. Others in the middle like R2/SG2, Magnacut, CPM154, Elmax, M390, etc all have carbides, excellent edge holding, but are harder to sharpen but are still very fine grained. Most of those steels have small carbides more evenly dispersed. AEB-L at 62-64 rockwell will perform and sharpen differently than AEB-L at 59-60.

So take a very fine grained stainless like AEB-L with few carbides or extremely fine carbides and they can take a screaming sharp edge providing the sharpener is up to the task. Higher hardness allows steels with lower carbide volumes to hold their edge better because all of the steel is harder, not just the carbides in the steel matrix and it will resist wear longer, and may have a more crisp precise edge than the toothier one.

More carbides often leads to a "toothier" feeling edge because the carbides wear slower than the metal matrix surrounding the carbides. Diamonds help reduce this, but even diamonds cut carbides slower than the steel matrix, so the edge may not be as even on a microscopic level. Tungsten Carbides can be around 80-90 Rockwell C (theoretically, most say the Rockwell C Scale ends at 70 HRC) when the surrounding steel is say 64. So when you sharpen, the carbides can provide more toothy edges and the edge won't feel as refined/sharp at higher grits. At say a 3000 grit edge, you may not notice a difference. At a 16K or 20K edge, you may be able to see/feel more of the difference.

Honyaki are water quenched blades, typically mono steel. The area above the Hamons is typically where the stamp/chiseling of the maker is done, which is why it's left soft so they can chisel their kanji. It gives some toughness to the blade, but the area is often relatively small compared to the rest of the blade, so I am not sure how much this effects the overall toughness. Stainless blade steels typically do not like water quenching typically, but can be made fully hardened, mono steel, which some consider honyaki.

Modern stainless steels with very fine grained carbides perform extremely well, hold their edge better, but are harder to sharpen and may need diamond or higher end stones. This leads to people saying that stainless don't take an edge well, and don't get as sharp as carbon steels. Usually it's operator or equipment error, not always the fault of the steel!

Hope this makes sense; I'm 12 hours into a 16 hour shift currently and have been up all night!

[salemj]

https://youtu.be/v8xK69vWITk?si=oOHMSDYz3W2X7-bY

I watched two of his videos. Very interesting. I think my primary comment here is that I really enjoyed them. Science is science precisely because it is not wholistic, but rather highly selective, in its goal of limiting any test to a single variable at a time. This is one reason it is difficult to really talk about these questions given the numbers of variables involved (for example, in terms of edge retention, the question of variables itself a problem [number of mediums, types of cuts, pressure/technique of cuts], with the bigger problem being that the more you "control" these factors, the farther you get from normal use scenarios).

I really like how both the video and (especially) Taz stress that, while science plays a major role in helping us understand the steel and its properties, experience and logic also play a role in reminding us that things like edge retention almost certainly DO vary with the quality of a heat treat and not just the number, even if we haven't quite found the best way of testing that yet in a quantitative fashion. There is such a thing as bad science, but usually, things we consider bad science are not necessary bad science...they are just experiments that look so specifically at a single variable that they can contradict more wholistic approaches. I think the part of the video related to edge retention is an excellent example of this: the approach seems really solid and provides really great results, but we can't help but also say "hmm...those edges all LOOK different and we know they should ACT different, so clearly this test isn't aligning with out actual experience of things in the kitchen..." That doesn't mean the science is bad or unreliable. It still eliminates a lot of factors in finding an approach test and in understanding the edges. In the end, I think it is still super-useful and will get us closer to finding a better set of variable or testing strategy, and wish some nay-sayers were maybe more optimistic about it all!

[taz575]

His video makes sense. The wear resistance when tested alone is the same because the hardness is the same. The edge holding test doesn't really test the grain structure, grain size, etc, so the steel is the same hardness and tests similarly. The edge wasn't stressed enough to make grain structure/toughness come into play. When testing for toughness and edge stability, the different shows more clearly.

CATRA testing shows edge holding, using coupons with the same shape, grind, thickness, etc, against the same medium. But the edges are fairly coarse (usually 400 grit diamond edge) compared to what we use in the kitchen and the testing medium is somewhat abrasive, so it's not always relative. People like cutting paper and cardboard and rope to test edge retention, but they aren't always equal samples. But it allows you to compare steels to each other at some level. Larrin Thomas did an excellent article here: https://knifesteelnerds.com/2020/05/01/ ... fe-steels/

I think when he tested the steels at different rockwell hardness, you see interesting results. Look at AEB-L, S30V and 10V and how they jump at higher hardnesses. AEB-L is a lower carbon steel with very fine grain, and it really jumped edge retention wise at higher hardness, but still has decent toughness. Simple carbons may have the same benefits of higher hardness and better edge holding as well, so I want to play with that a bit. IE 52100, 80CRV2, AEB-L and Nitro V at like 63-65 HRC. I know a guy running AEB-L at 64 and loves it. Those may not be practical hardness values for every day knives, but they may work well for kitchen knives that don't see prying and more abusive tasks. Lets face is, what we cut in the kitchen isn't super abrasive and with a good, softer board to cushion the board impact, we can probably push the hardness up a bit compared to an EDC blade! With simple steels with less carbides, they are still somewhat easy to sharpen at higher hardness than something like S90V at 61.

Some of the higher end kitchen knife steels are between 5 and 10 toughness (sg2/R2/VG-10) at 61 rockwell, but something like CruWear at 64 is still much tougher (14 ish)! With my new oven, I can do some testing and FINALLY use the APEX Ultra steel bars I picked up. I need to forge them down a bit since they are .20" thick, but now I can do the full normalizing and annealing processes (my other kiln wouldn't go hot enough) and get some high hardness (66-68 rockwell) in a simple carbon steel that should be easier to sharpen and still have toughness to hold a fine edge in a kitchen knife.

[Kowalski_Boston]

Wow! Lots of replies. It took me a while to find time to chew through all this.

Hello. Are you in the Boston Mass area too?

Yes I am.

Most of the information you cite lacks nuance and subtlety.

Well, yes it does. I collecting information to buy specifically Fuguhiki knife, hence really taking notes from various sources what relates to it and discarding what not. This is by no means any academic discussion on metallurgy in general, but very narrow look shaped by my particular needs, lack of understanding and my misconceptions.
Information about mono steel, Honyaki and Kasumitogi I took from Gemini (Google AI) and very, very long Honyaki tread, partially hijacked by what appeared to be knife makers (most of their post could not be understood by average Joe like me) on Reddit. I have not bookmarked it (tried finding it again but there are many Honyaki treads there). Anyway people in that particular tread were posting pictures of insanely thin, acute angle profiles of their Yanagiba Honyakis (sometimes along pictures of visibly thicker and higher angles of mono steels they also owe), and swearing Honyaki were the sharpest smoothest cutters.
When thinking of slicers (Yanagiba, Fuguhiki, Sujihiki, Takobiki), you thinking, very soft, delicate texture, where very clean (no tears or micro tears) cut is a goal. Also (at least to me) little to no contact with board is expected, hence, higher brittleness (within limit of practicality, you don’t want to leave chips from edge in the meat) is OK, if it can make more extreme sharpness (I would imagine somewhere in vicinity, or even better below 50 on edge on tester).
To my understanding in sashimi slicers in general, it is understood that mirror polished edge without teeth offers best performance and that what is needed.
That said, I often stumble on statements (again in regard to sashimi slicers), where people seems to use either edge retention or ease of sharpening interchangeably with sharpness or “performance”. It probably makes some sense considering professional chefs, to whom heavy use and need to hold edge sharp at minimum effort is very important (you don’t want to sharpen your knives say 10, 20 or more minutes at a time, few times a day in front of customers). For home “chef” like me edge retention and ease of sharpening (even not meaningless) are of lesser importance (as long as knife can hold edge and be possible to sharpen so it’s practical for light use - that’s fine with me. Longer sharpening, more frequent is OK).
To be honest I was not even aware there are not differentially hardened Honyakis? What’s the process and advantages of it?
In any case thank You very much for long in depth explanation. Yes it did help a lot. I find it close to impossible to Google any source information on subject and knowledge usually comes from various YouTube videos and forum’s discussions, while obviously, some papers I stumble upon once in a while too technical to chew on.

Two identical steels can be treated to an identical Rockwell hardness; however, they may not have the same heat treatment.

What good heat treatment exactly improves? From information I absorbed (perhaps have some misconception) it is some vaguely described “balance” of hardness, durability, grain structure and edge retention (last supposedly, unless you go what Outdoors55 show in YouTube link below). Lots of people seem to use all the time term “good heat treatment”, where it seems very vague what it really means. Why heat treat slicers at all?

Higher hardness (with correctly sized grain structure for the steel) will allow an edge to remain intact longer, providing there is sufficient toughness at that hardness to keep the edge from rolling or crumbling. You can get the same HRC with different heat treat recipes that has been said, but the internal structure is equally as important! A steel may be brittle with large grain at 64 HRC, or much finer grained and tougher at 64 HRC based on how it was heat treated. Higher hardness with fine grain structure may feel "sharper" because the edge is more uniform and consistent if it's not "crumbling", so some equate higher hardness with sharper feeling, unless they have an edge that wears/crumbles easily, which usually means it brittle. Harder edges often deburr better (less gummy), so it maybe easier for people to get them properly sharpened than softer/gummier steels, regardless of the carbide content.

Carbon steels (Blue and White) have a very fine grain structure to them, but not much carbide content. They take a wickedly fine edge easily, but edge retention is lesser. There are more highly alloyed carbon/tool steels that have more alloys to them which can make sharpening more difficult and the edge may not feel as sharp and the grain structure isn't quite as fine. To get better edge retention, the hardness may be bumped up instead of having carbide formers present in the steel.

Stainless steels vary a lot. Some are very fine grained (AEB-L, which also doesn't have much carbides in it), others are much coarser grained (D2, VG-10) typically, but have carbides for better wear resistance. Others in the middle like R2/SG2, Magnacut, CPM154, Elmax, M390, etc all have carbides, excellent edge holding, but are harder to sharpen but are still very fine grained. Most of those steels have small carbides more evenly dispersed. AEB-L at 62-64 rockwell will perform and sharpen differently than AEB-L at 59-60.

So take a very fine grained stainless like AEB-L with few carbides or extremely fine carbides and they can take a screaming sharp edge providing the sharpener is up to the task. Higher hardness allows steels with lower carbide volumes to hold their edge better because all of the steel is harder, not just the carbides in the steel matrix and it will resist wear longer, and may have a more crisp precise edge than the toothier one.

More carbides often leads to a "toothier" feeling edge because the carbides wear slower than the metal matrix surrounding the carbides. Diamonds help reduce this, but even diamonds cut carbides slower than the steel matrix, so the edge may not be as even on a microscopic level. Tungsten Carbides can be around 80-90 Rockwell C (theoretically, most say the Rockwell C Scale ends at 70 HRC) when the surrounding steel is say 64. So when you sharpen, the carbides can provide more toothy edges and the edge won't feel as refined/sharp at higher grits. At say a 3000 grit edge, you may not notice a difference. At a 16K or 20K edge, you may be able to see/feel more of the difference.

Honyaki are water quenched blades, typically mono steel. The area above the Hamons is typically where the stamp/chiseling of the maker is done, which is why it's left soft so they can chisel their kanji. It gives some toughness to the blade, but the area is often relatively small compared to the rest of the blade, so I am not sure how much this effects the overall toughness. Stainless blade steels typically do not like water quenching typically, but can be made fully hardened, mono steel, which some consider honyaki.

Modern stainless steels with very fine grained carbides perform extremely well, hold their edge better, but are harder to sharpen and may need diamond or higher end stones. This leads to people saying that stainless don't take an edge well, and don't get as sharp as carbon steels. Usually it's operator or equipment error, not always the fault of the steel!

Hope this makes sense; I'm 12 hours into a 16 hour shift currently and have been up all night!

Wow! Very in-depth explanation. I’m not sure I am able to grasp all, but (if I understand correctly), and what other people also seem to hint before, good stainless steel can be as sharp as carbon. Now in particular case of Fuguhiki, where I don’t want teeth but mirror edge (I suppose) which particular steel should I look for? I have heard of AEB-L long before but not seen any Fuguhiki made of it. If I could get crazy sharp stainless Fuguhiki I would definitely go for it instead of carbon.

I was told once, on this forum, here:

https://www.chefknivestogoforums.com/vi ... 14#p156114

Quote: “As far as steel etc.
SHARP is all that matters with sushi.
Dont forsake this for steel type or ease of maintenance.”

I also received following reply to same question on Reddit:

https://www.reddit.com/r/japaneseknives/s/GeOFzZSMzM

Quote: “So to be very sharp you can’t be stainless and you must be hard. That’s why people tend to say the sharpest edge comme from white 1 that can be treated hard and is very « pure » (no chromium, molybdenum, vanadium …)”

Besides I see, professionals usually opt for carbon:

https://thejapanesefoodlab.com/rust/

That said, as mentioned before, it’s quite possible professionals opt for carbon because of heavy use and concerns which go along with it.

[Kowalski_Boston]

To summarize. Good stainless steel (if available for particular knife I looking for - guessing good steel spells good small grain structure), hard (sharpening it few hours on diamonds in progression to very high grids it’s OK - as long as it can hold edge to be practical for use), with good heat treatment (where the only clue to get one, is look for craftsman HT in small batches - that might be difficult to find/know), will provide as sharp edge (somewhere below 70 on edge on tester) as carbon. Am I correct?

[taz575]

Ah, Fuguhiki! That is a very specialized type of blade, so your original questions makes a bit more sense now. They typically have very high polish on them and are thinner and narrower than a yanagiba and are wickedly thin behind the edge. I have seen them in VG-10 and Ginsan 3 before online; I would check out a G3 version since the VG-10 can have larger carbides in the steel, which will feel like a coarser edge possibly. Ginsan 3 is a very fine grained stainless that should work well in this application versus carbon steels like white and blue. For these knives, people often go to super fine grits to really fully polish the edge to a mirror finish. It's not a general purpose kitchen knife that's good a 3-5K for the edge or where you want tooth for tomato skins. G3 was supposedly created to be a stainless steel with the benefits of carbon (fine edge taking, easier to sharpen, etc).

AEB-L (13C26) also comes to mind because it was designed as a stainless razor blade steel where they looked for very very fine grain structure, no real large carbides/carbide formers, and toughness so it can be taken to a higher hardness and still be a viable blade, and one that is easier to polish and sharpen. IE all of the benefits of carbon steel, but a stainless steel. They aren't as worried about edge retention, and use the higher steel hardness in lieu of carbides to increase edge retention since the blade doesn't need toughness (razors and Fuguhiki are similar in this regard). You probably would want AEB-L in the 62-64 HRC range, and G3 in the 62 ish range. Most factories don't run the steels that hard, but G3 will be easier to find in a Japanese made blade than AEB-L at the higher hardness.

So look for a G3 or AEB-L/13C26 Fugihiki at 62 or higher hardness.

Speaking of grain struture, these pictures from Larrin Thomas show the white carbide blobs and their relative size in 3 different stainless steels:

VG-10 grain, the white splotches are carbides:

SG2/R2 grain structure:

AEB-L grain structure, notice the carbides are very tiny!

And a simple carbon steel 80CRV2. This picture is at twice the magnification as the others, but you can see there is very little carbide at all, even at twice the magnification. When you are polishing and looking for the absolute finest grain structure, this is why the simple, unalloyed carbons are very tough to beat!

[Radar53]

What a great post & many thanks to all the contributors. It makes wish I had paid more attention a university during the "Science of Materials " course unit I took

[Kowalski_Boston]

Also would like to thank all contributors for very knowledgeable in-depth answers.
In many months of searching for Fuguhiki I only once seen some “unknown” Swedish steel listed, don’t even remember was it particularly for Fuguhiki. Guess is nobody is making AEL Fuguhikis.

I’m still torn apart between opting for G3 or Kasumitogi with Carbon steel Hagane. Concerned little bit, since G3 is harder to heat treat, how good HT will be in lower-medium price range, while, at the same time, fighting with rust (and living with Patina) just on edge, seems as not that terrible prospect.
Thank You very much everybody for your help!

[salemj]

Also would like to thank all contributors for very knowledgeable in-depth answers.
In many months of searching for Fuguhiki I only once seen some “unknown” Swedish steel listed, don’t even remember was it particularly for Fuguhiki. Guess is nobody is making AEL Fuguhikis.

I’m still torn apart between opting for G3 or Kasumitogi with Carbon steel Hagane. Concerned little bit, since G3 is harder to heat treat, how good HT will be in lower-medium price range, while, at the same time, fighting with rust (and living with Patina) just on edge, seems as not that terrible prospect.
Thank You very much everybody for your help!

I'm not sure what you mean by "lower price range," but I'd encourage you to think of price as more related to material costs first, and grind/geometry/fit and finish second, with heat treatment being a distant third. Many of the best smiths have made (or do make) knives in lower price ranges anonymously (or at least they try to). And many lower-priced knives have very good heat treatments. Some excellent heat treatments are virtually automated now, too.
What you see MUCH less of are lower-priced knives that have tremendous grinds, tremendous fit and finish, or more expensive steels.

That said, G3 might be more expensive as raw material than other options. However, I'd guess the steel is now pre-laminated, as there are decent "budget" options below 150 USD. The weakness of the Yen versus the Dollar helps here, too.

[Kerneldrop]

The folks making Tsunehisa and the 10+ other names made in the plant will have consistent and automated heat treat. You can trust it. Mine sharpens like a dream and gets very sharp. I have the Yahiko 240 gyuto Ginsan.

[taz575]

I wouldn't be worried about the heat treat quality with a major company using a known steel. Lower priced is usually material cost. I send blades out for heat treating and larger batches mean less cost per blade. 100 blades is $5/blade, 4 blades is also $100 per blade, for the exact same heat treat/cryo in a top notch facility that I use. Stainless steels have a more complicated heat treat, but is easy to do with the right equipment. Most stainless steels are run in digital controlled ovens/kilns and have a more precise heat treating schedule than carbon steels. Some Japanese makers may do carbon steels differently (in the forge by eye), which can lead to under/over heating and less precision across the batch. Some steels are more forgiving than others are! For non air quench steels (ie Oil and Water/brine), the temperature of the quenchant has a big role to play; too hot or cold and the blade may not harden properly/fully. Air Quenching steels are more forgiving since they have minutes to cool down below a certain temperature where carbon steels usually need to cool below a certain temperature in seconds, not minutes.


In most Japanese knives, heat treating is spot on and at the appropriate hardness for performance; they understand how important it is and run proper hardness levels for the steel and useage. Other places/countries often go softer in the Heat Treat for better durability and easier machining/finishing (typically pocket/hunting/camping/edc/western kitchen knives), but I have noticed that most Japanese companies run higher hardness on par with custom knives.

[Kowalski_Boston]

Well, so You have persuaded me! After much looking I am about to buy either of following two:

https://www.tadokorohamono-marushin888. ... 包丁-フグ引剣型包丁

https://www.tadokorohamono-marushin888. ... グ引包丁-てっさ包丁

No matter which, in both cases it will be Silver-3 (G3), rosewood handle, buffalo horn ring, mirror finish, with Honbazuke (increased edge angle to more acute) performed by Makato Tadokoro (30 years experience sharpener. By number of materials on Internet in general about him, he appears to be well known and established craftsman. Knifes comes from his company directly - Marushin in Tosa Japan)

Honbazuke, mirror polish and buffalo ring are extra charge.

I originally thought Rockwell hardness was 62-63, cannot find it listed anymore so not sure, seen it or false memory, will e-mail them to confirm.

They also mention in e-mail reply some “EMS shipping fee, charged separately” - whatever that is (?).

Total price will depend on ¥ to $ exchange rate. When I last looked in Google it was ¥157 = $1, now is says 142.30…. unfortunately.

As always, knowledgeable comments appreciated.

[Kowalski_Boston]

AFTER EDIT:
Forgot to mention, I also supplied myself with sharpening stones.

So far I have:
1. Sharpal double side (325,1000) diamond plate (recommend by Outdoors55 on YouTube). 325 grid more for fixing things rather than sharpening, still decided I want it for other knives and in general. According to Outdoor55 it is only diamond plate not contaminated with lower grid impurities. Washing it with water (against recommendation) to ensure no cross-contamination after each use. Will also think of it as my flattening stone for splash and go:
https://a.co/d/6FPlOGQ

2. Arashiyama 1k splash and go. Assuming it’s a same thing as YouTube recommended Imanishi Arashiyama 1000. Might not be biting enough (will see) for hard G3, still one way or another I still want it anyway for other knives I have.

https://secure.chefknivestogo.com/OS/st ... 256ab0ff0a

3. Sherpal’s double side leather strop (after watching YouTube I was close to making my own strop, however after rethinking, information there might be possibly old. Strops are cheap, probably not worth hassle of making):
https://a.co/d/eQlxaUu

4. Jende 1 micron Poly diamond emulsion (brand recommended by Outdoor55)

https://a.co/d/gpby44I

5. Kangaroo Leather Strop. Bought by mistake. Wasn’t aware what size is it and in the size it is, is close to useless for me. Dirtied the box so it stayed.

https://a.co/d/4JmeIKa

I imagine I will also need middle/high grid (5000/10k) diamonds plates for sharpening, than entire set up for eventual mirror restoration in future (haven’t decided yet diamond plates some stones, papers or strops with diamond emulsions). I’m prepared mentally for gargantuan task of restoring high mirror on hard steel (quietly hoping won’t ever need it). Since G3 is semi stainless intending on observing all stain procedures as if it was carbon (cleaned and dried after each cut, no acidic substances, storing in dry place). I really don’t have need for cutting with this knife anything beside fish and seafood (scallops, clams, octopus, squid, cuttlefish - and similar), where I even considering possibility of making last, board touching cut with different knife (so it doesn’t touch ever any board at all). What I really need is extreme sharpness, needed for Usuzukuri, very soft textures cut cleanly to ultra thin film thickness. Perhaps overkill, once I get it will decide.

As always appreciating all words of wisdom. Might be wrong place to post all this, however since people here seem to really have high expertise, just thought it won’t hurt.

[Kowalski_Boston]

UPDATE: back to square one. While digging through Marushin website for G3 hardness (which I could swear I’ve seen somewhere) I found instead some worrying information - the table showing properties of their steels:

https://www.tadokorohamono-marushin888.com/en/trivia

It is in Japanese so here is picture of it translated with Google Translate:



As You can see Ginsen steel is listed, by seller,… as least sharp with only three stars.
It’s not the first Japanese seller which shows G3 as not particularly sharp. Another worrying indicator is “hardness and durability” listed as two stars. It is bit confusing that hardness and durability are listed together, as those two seem to be completely different properties. Nevertheless, further clues can be picked reading Ginsen steel description immediately below, where they saying using wet stones for sharpening makes sharpening easy (Easy? Wet stones? Not diamond plates and harder to sharpen?)

One way or another bottom line is: if master sharpener, with 30 years experience says he cannot make knife he sells in particular steel top sharp, it probably cannot be made.

Watching at another G3 Fuguhiki at different seller’s websites, and yet another steel comparison table, again Ginsen is rated as less sharp than carbon:

https://www.tablinstore.info/phone/product/3663

Its bit confusing understanding what it all means? I have no reason to doubt information provided in this tread previously. But why Ginsen is listed again and again as less sharp? Is it heat treatment which doesn’t bring this steel to higher hardness or some other parameter? One way or another am bit hesitant to trust other sellers which doesn’t have similar tables will be offering particular hardness G3 which, yes, will be possible to make as sharp as say white1.