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 Post subject: Intro to Japanese style knives Primer
PostPosted: Sat Nov 08, 2014 3:42 pm 
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Joined: Thu Apr 26, 2012 5:13 pm
Posts: 3105
Location: CT
So you got your first Japanese knife and notice it's a bit different than your Henckels and Wustoff's! Here is some info to get you started. Let's start on the blade first.

You will probably notice that the blade is thinner and lighter than the German styled counterpart. Japanese knives are often thinner and harder than the European styled blades. Because of this, frozen foods and bones should not be cut with Japanese knives! Same with hacking up big blocks of chocolate, lobster/crab shells, etc. Certain knives are better for these tasks and you need to use them a certain way, so for now, keep one of the older, softer, heavier knives around for these tasks as your "beater" knife! Also, Japanese blades should all be washed and towel dried after use BY HAND, NO DISHWASHERS!!!!; even stainless can still rust if left wet!

You may also notice the the blade is not symmetrically ground (50/50). On many Japanese knives, the bevel on the right side may be further up the blade or more pronounced than the blade bevel on the left side (as you hold the knife like it's in use). This allows for a finer edge and brings the cutting edge closer to the food being cut from, which allows thinner slices to be made easier. Also, with the right side having more convexing to it and a deeper grind, this will force foods away from the blade more, which may mean less food stuck on the blade. The blades are often a 60/40 or 70/30 grind. Lefties, sorry, but this many mean some steering for you. Loosen up your blade grip and as you use the knife, you will see how to compensate.

You may notice that the blade doesn't have the legendary sharpness you expect from the culture that brought the Katana into the world that can slice a silk scarf as it falls over the blade. The Japanese manufacturers know that each customer is different and they let them finish off the blade edge to their liking. Some like a 1-2K edge thats very toothy, others strop up to 124,000 grit for a very polished edge. 3-6K is where most kitchen users like their edges to be. So how do you sharpen?

No Chefs Choice, no Tungsten blade thingies that peel metal from the edge, no Norton India stones that look like a cinderblock!!! Certainly no metal "honing rods" that you whip back and forth across the edge like a mad man!! Waterstones are the way the go here! Water is used and the abrasives break down to expose fresh abrasive, which means they work quickly, even on the harder steels. A 1000 stone is good for light thinning, small chip removal and setting/refining the edge bevel. You can shave off of a good 1000 grit edge and it's close to how the factory ships them normally. A finer stone in the 2K-6K range is the next stone to get to refine your edge further. The finer stone can also be used for quick touch up and stropping to maintain a fine edge without need to go back to the 1K stone as often. If you get big chips or the knife is wedging and needs to the thinned a stone in the 300-500 range would be good, but most people starting
out don't
need one immediately. A hard felt block can be used to remove the wire edge/deburr the edge, but a leather strop can do the same thing and you can add compounds to further refine your edge. Between stropping on leather and your finest stone, you can go a while before you need to go back to the 1K stone as a home user! A fine grit ceramic steel like the Idahone can also be used to touch up, but use VERY LIGHT pressure. A ceramic rod has little area of contact on the blade and too much pressure can chip the hard, thin edge. On a European knife, the edge rolls back and forth and the steel re aligns the edge so it will be "sharp" again. On a Japanese blade, this can chip the blade.

Why are the spine and Choil areas of the blade sharper than the blade itself? Most Japanese manufacturers let the end user clean up these areas as needed. Some will use a file to break the edge, others leave it sharp, others round it out nicely. Fine files and sandpaper takes care of this pretty quickly. Some importers have the manufacturers clean up these areas before they ship since many customers outside of Japan are used to a higher level of fit and finish.

The blade itself may show hammer and grind marks, especially on certain styles of knives, like Kurouchi, Tsuchime and Nashiji blades. The blades are often forged out and there is often a slight hollow formed into the upper half or more of the blade to aid in food release and weight reduction. The blade grind itself may have slight ripples/dips in it. Many manufacturers still grind their blades on large (3' diameter) stones and the grind is not always perfectly flat. Most will flatten out in a few sharpenings and the dips/ripples aren't an issue unless they happen at the very edge, this can lead to a "hole" in the edge of the blade while sharpening.

Sometimes, like on Honyaki Blades or Kurouchi blades, there is an extra lacquer coating to help keep the blade protected while in transit/storage. On Honyaki blades, it shows as a rainbow like tinge and it's harder to see on Kurouchi blades. Most just sharpen it away at the edge only since it helps to keep the carbon blades from reacting to moisture/foods as quickly.

Now let's move on to the handle. Western handles may have swollen/shrunk and the edges of the tang may have gotten exposed, even though the handle materials used are relatively stable. This tends to happen a lot, especially in very warm or very damp climates. Most people sand the handles down if they are uncomfortable to round out or ease the edges/sharp corners. On Wa handles, there are a few more questions that often get raised.

The first is the fit of the ferrule/collar to the handle. There will often be a gap between these two since neither material is usually stabilized and can swell and shrink with moisture/humidity. Ho and Magnolia wood were traditionally used because they held up very well to the moist kitchen environment and didn't rot when they got wet. Also, the grain tends to stand straight up when wet, adding extra traction to the handle. The wood will often feel fuzzy even after it dries. This is normal. If you don't like it, sand the handle with some 320-600 grit sandpaper and use an oil finish on it to seal the pores and keep the grain from raising. Some collars are plastic and can become loose or come off completely due to the swelling/shrinking of the handle over time. Super Glue Gel or 2 part epoxies work great for fixing loose or falling off plastic ferrules.

Higher end handles, like the Rosewood Takeda handles, Yew handles, Ebony Kono handles, etc are less affected by moisture and are sealed better from the factory. These handles also exhibit better fit and finish as well compared to the majority of the buffalo horn/Ho handles.

Japanese handles may also show a gap between the tang of the knife at the Machi (notches top and bottom of the tang on the neck) and the ferrule. This is to allow the handle to be tapper further up the handle as it loosens over time. Most handles have a pilot hole drilled into the handle and the knife tang is heated up and burned into the knife handle. These handles can loosen up over time. Many manufacturers are now using epoxy or rubbery sealants inside the handles and on the tang and the end of the handle to prevent moisture from getting into the handle and to keep the handle from coming loose.

Oval and Octagon handles are the most comfy for lefty users, but many lefties find that D handles do not bother them. They can also sand the D protrusion down or remove the handle, flip it so the D is on the left side and re install.

Why use an inexpensive handle on an expensive blade? The Japanese are very practical. They have upgraded handles if you want them, but they would rather put the effort into the blade than a handle that is viewed as a disposable item and is meant to be replaced as often as needed.

There is a term called "Wabi Sabi" in their culture and it refers to something being handmade and having small imperfections being valued over a "perfect" machine made, sterile item. This is why the Japanese users are OK with the spine/choil not being rounded, the blade not being fully sharpened, minor handle issues, dips/ripples in the blade grind, etc. All of these small imperfections show that the knife was hand made, which they like to see. Customers outside of Japan see these as fit and finish issues because we expect everything to be perfectly fit and polished, perfectly even grinds and super sharp out of the box.

Now on to explaining more about the grinds, finishes, steels, etc of these knives!

Japanese knives have a wide variety of grinds to them. The grind refers to how the vertical sides of the blades are shaped and is often referred to as Geometry. Some are a full grind, where the grind starts at the spine and ends at the edge. This is often seen as a Flat Grind, where the grind is flat, or a Convex Grind, where there is some curving of the blade surface as it tapers from the spine to the edge.

Many knives, especially Single Bevel Knives and Kurouchi Finished knives, have a type of a Saber Grind. This is when the grind does not reach the spine of the knife and often stops just shy of halfway up the blade. It may be a convex or a flat grind, or even a slight hollow grind! Many Japanese knives are ground on very large stone wheels, which gives the grind a very slightly hollow. It is blended in very well usually and the end user generally doesn't realize it is slightly hollow until they go to flatten the blade road and find that the stone doesn't contact the blade evenly; the deepest hollow I usually see are right below the Shinogi line or in the middle of the blade road. The Blade Road refers to the ground part of the blade in a Saber ground knife. The Shinogi line refers to the often sharp line between the blade road and the remaining part of the blade, which may be flat or concaved slightly. A Shinogi line can best be seen in single bevel knives.

Single bevel knives come in 2 varieties. One of the varieties is one side ground like a Saber Grind, and the other side mostly flat. This is often seen in Honesuki's and some smaller, less expensive Deba's. They are sometimes referred to as a 90/10 grind. The more common variety is the Saber grind on one side and a hollow side on the other; the edge itself is offset and placed closer to the back of the knife (the hollow side or Urasuki). This is commonly found on the Deba, Usuba, and Yanagiba, as well as a traditional Kiritsuke. This allows the edge to get a little sharper and the cutting edge is closer to the hollow back side, allowing for cleaner slicing. These knives are generally used for sushi tasks and are not a general use item. Due to the edges being very thin, they are easy to damage if your skills aren't up to the tasks!

Double bevel knives are the more common petty (paring/utility knife), Gyuto (180-300mm long, with 210mm-270mm being the most common), Sujihiki (slicing knife), Nakiri (thin veggie knife) and Santoku (stubbier pointed short gyuto with a flatter edge profile). Most double bevel knives are not ground evenly (50/50) on both sides. Some are 60/40, 70/30, 80/20, etc. Most of these grinds favor a more strongly ground right side of the blade (point away from you, edge down) and a flatter ground left side of the blade. This allows for a more acute edge and it's easier to make very thin cuts since it brings the edge closer to the item being cut. I have seen some knives where they are ground with the stronger convex on the left side. Steering may be an issue depending on the actual grind, your grip, what you are cutting and how you are cutting. A looser grip, shorter height ingredients, and being used to the knife and unconsciously compensating all factor in to reduce steering.

A choil shot is referred to quite often when talking about the grind or geometry of a blade. A choil shot will usually show what the geometry of the knife looks like from the bottom of the handle down to the actual edge. A choil shot can be misleading if the knife blade isn’t perfectly perpendicular and the camera isn’t perfectly lined up with the blade. Also, the choil shot doesn’t show the area of the blade that the handle blocks. The concave/convex grinds are sometimes hard to see in a choil shot, and you need a true flat edge to see what the grind looks like. But it will give a general idea of how the knife was ground and how thin it is behind the edge.

In this pic, you can see that on the grind on the left side of the pic (right hand side of the knife in use) is ground past the 50/50 point and has more convexing than the other side of the blade: ... ri210c.jpg

This pic shows the slight concave grind on the left side of the pic and the convexing on the right side of the pic: ... l.jpg.html

This choil shot shows the start of the concave portion above the main blade grind and the mostly flat blade road: ... l.jpg.html

Surface finishes:
Many Japanese knives have a “Satin” finish, which is where the scratch marks run perpendicular to the edge. Some knives have a hand rubbed finish, where the surface scratches run parallel to the edge (down the length of the blade). Others are polished to a mirror finish. Other knives have what is known as a Tsuchime, which is a hammered or dimpled finish. This is to help lessen the drag/friction of the blade in the cut and also make food release better. A Nashiji finish or Pear Skin) refers to the light texture on the outer most steel layer; it serves a similar purpose to the Tsuchime.

A Kurouchi finish is a “blacksmith finish” and is usually black or blu-ish in color. It is from a coating put on the blade while forging/heat treating that leaves a dark surface on the blade, often along with the forging scale. The surface underneath is slightly rough/textured and the Kurouchi finish helps keep the steel (usually a softer carbon steel or stainless steel cladding) from reacting/oxidizing with foods. Some Kurouchi finishes look powdery, others are shiny, other look like Gun Bluing. There are numerous varieties of Kurouchi finishes. Kurouchi finishes are sometimes done over dimpled cladding or even done on Stainless cladding. Since the blade is not polished, it reduces the working time/cost a maker puts into the knife. Kurouchi finishes can and do wear off with time.

A Kasumi finish is a misty finish that shows off the contrast between the harder hagane (core steel) and the softer jigane (softer cladding). Many manufacturers bead blast these areas since the harder steel will not be affected as much as the softer cladding and will show a difference easily. The bead blasting can feel rough and add extra drag to the cutting stroke. I use a non woven abrasive pad to keep the kasumi look, but smooth out the blasted area.

This picture shows the harder core steel at the edge, the bead blasted Kasumi finish between the Shonogi line and the edge and the more polished upper portion of the blade: ... 5/RAS6.jpg

Another way to produce a Kasumi finish is from using waterstones; this method takes a lot longer is isn’t often found on most production knives!

This picture shows a Kasumi finish off of a King 800 stone. The harder core steel takes on a brighter finish/shine and the softer core steel will tend to take on a darker, more matte look. Some stones lighten up the cladding so it is not as dark, but still matte looking. Japanese Natural Stones and synthetic water stones are used in this process and each stone works different steels differently. ... cf5751.jpg

Stone finishes can be taken up to a very high level and near mirror finishes, but it takes a lot of time and patience.

Knife Construction: There are 2 basic versions of construction. The first one is a Mono Steel construction. This uses 1 piece of steel for the whole knife. Honyaki knives are mono steel and many of the “Laser” type of knives are mono steel. The whole blade (except for Honyaki, see below) is hardened.

The second construction is a Clad Blade construction. A clad blade that has 2 layers of steel, 1 hard and 1 soft (in a single bevel knife) is known as Ni-Mae Awase. More common is the San Mai Awase, where there is a hard core steel with a piece of softer cladding steel on each side and is found in double bevel knives. The cladding can be stainless steel, carbon steel, wrought iron, etc. Sometimes the cladding can be a stainless or carbon steel that is layered up and when ground, looks like Damascus. San Mai blades will have the core/cladding visible at the spine normally, especially in carbon core/stainless clad blades since the core will still patina. The third type of cladding is Warikomi Awase, and the hard core is wrapped around by the softer cladding on double beveled knives. This 3rd type is not as common as the San Mai. The clad blades reduce cost since there is less of the harder, more expensive steel in the knife. Sharpening is also easier because you are working on a thinner piece of hard steel; the cladding sharpens away easier than hard steel. The clad construction also can mute the feedback/feel of the knife on the board; some people notice it, others do not. Some prefer the feel of a clad knife, others prefer the feel of the Mono steel knife. On any clad knife, there will be a lamination line present between the hard and soft steels. Different finishes bring this out (see Kasumi finishes). Carbon core steel in stainless cladding will show a sharp contrast once the core steel has patina’d and darkened. This wavy line is not a Hamon line however!

Honyaki Blades: These are typically constructed a little differently than a regular mono steel knife. They are often forged out of one piece of steel and when the knife is heat treated, the blade is covered in clay in varying thicknesses and then quenched in water. The clay helps prevent the area covered in the thickest part (usually near the spine) from fully hardening and this is where the kanji are often inscribed/chiseled. Honyaki knives are taken to a higher hardness than other knives and will hold their edge longer. However, since they are harder, they are a bit more brittle than other blades and are harder to sharpen, grind, polish, etc. The water quenching method adds a lot of stress to the steel during that phase before tempering and many knives end up cracking or warping during this process. Sometimes only 1 out of 3 Honyaki blades survive the heat treating process. Honyaki blades are generally much more expensive than other mono steel knives. Suisin Inox Honyaki are mono steel knives, but stainless steels generally are not differentially hardened and do not display a Hamon line.

Hamon Lines: These are often found on Honyaki knives (and swords) and denote the hard/soft steel areas from the heat treating. They can be straight, wavy or a multitude of patterns. The area that is softer is generally has a cloudier look to it and the harder area is generally a brighter polished look. Etching and polishing the blade with stones will bring out the hamon line. A Hamon line is different from a cladding line.

The bottom knife in this picture is a Honyaki knife and shows a very prominent Hamon line in a wavy pattern: ... asWIP3.jpg

Laser: A “laser” type knife is one that is generally very thin at both the spine and behind the edge. It will slip through foods easily, but has little to no convexing, so it may wedge in harder foods. Konosuke HD, HH, White #2, and Sakai Yasuke are classic examples of “lasers”.

Workhorse: A workhorse knife is one that is thicker at the spine and behind the edge and has a strong convex grind to the sides of the blade. It may have more resistance while cutting, but the heavier weight and stronger convexing give it a more powerful feel while cutting and it has better food release. It may wedge and crack through harder ingredients, like tall carrots and hard squashes. It is a bit beefier behind the edge than a Laser type knife, and can handle harder tasks, but should still not be used on bones or frozen foods. Kanehiro and Hiromoto AS are good examples of workhorse knives.

Midweight refers to a knife that combines aspects of the Laser and Workhorse. Slightly thicker spine and more weight than a Laser, but very thin behind the edge and has some of the convexing of the Workhorse without being overly thick. Tanaka Sekiso, Anryu Hammered & Richmond AS Laser are a perfect example of this.


Carbon steels: There are others, but these are the main ones we usually encounter in Japanese knives.

White #1, White #2, White #3 (Shirogami): Very pure carbon steels, little alloying elements (some manganese and silicon), little sulfur/phosphorus impurity in the steel. Very easy to sharpen, decent edge retention. White #1 has more carbon that White #2, White #2 has more carbon than White #3.

Blue #1, Blue #2 (Aogami): Pure carbon steels like White, but with Chromium and Tungsten for added wear resistance, slightly less reactivity than White steels. Slightly harder to sharpen compared to White steels.

Aogami Super/Blue Super: Blue Steel with higher carbon content, Chromium, Tungsten, Molybdenum and Vanadium. Better corrosion resistance, longer edge holding, may not take as fine of an edge as White #1.

SK3, SK4, SK5: Carbon steels with more phosphorus and sulfur impurities. Has some nickel, manganese, silicon, copper, chromium. SK3 has more carbon than SK4, etc. Entry level carbon steel, sometimes has a stinky smell when it reacts to foods until a patina sets in fully.

Semi Stainless: HD2 and in TKC blades. A semi stainless is a steel that has a high Chromium content, but not the 13% that is considered to make a steel “stainless”. These knives resist patina and react minimally to foods, and will often turn a dull grey color for the patina. They can still rust if left wet for long periods of time.

Stainless Steels: (they can still rust if left wet even though they are “stainless”!!)

AEB-L/13C26: Very fine grained stainless steel, few impurities. Excellent edge retention at 60-62 rockwell hardness, easy to sharpen and tough. Nice stainless steel to work with when it’s heat treated correctly (some Japanese factories leave it softer), and reviews having the edge being held through a week of work in a pro kitchen.

12C27: Another Swedish stainless steel, fine grained, good edge retention.

Ginsan3/G3/Ginsanko: Very fine grained Japanese stainless steel, pure steel, takes and holds a very nice edge, easy to sharpen.

AUS-8A: ChromeMoly steel, gets up to 59-60 rockwell, easy to sharpen, decent edge holding. Found in lesser expensive knives.

VG-10: Stainless steel, OK edge taking/holding, very difficult to deburr. Often chippy from most factories due to the heat treating. Very common, found in many entry level Japanese kitchen knives.

Super Steels:
ZDP-189/CowryX: Not the same steels, but both can be taken to very high hardnesses (66 Rockwell), and include many alloying elements (lots of carbon, chromium, tungsten, etc). Extreme edge retention, good toughness, a little harder to sharpen than other stainless steels.

SG2/R2/SRS15: Powder metal steels, very fine grain, lots of alloys, can be taken to high hardness (62-65). Extreme edge retention, a bit harder to sharpen than other stainless steels.

M390: Lots of Vanadium and Chromium, high wear resistance. Difficult to sharpen with slower stones.


Wa handle: A stick like handle, often has a dark ferrule/collar in the front and a lighter color wood (ho, Magnolia, yew) in the back. Buffalo Horn ferrule and Ho wood handle is the common type, but black dymondwood ferrule and rosewood is also popular (Takeda handles). Rosewood is harder to find and more expensive now, so makers are going with Yew and other inexpensive woods. Ho and Magnolia wood fair very well in a kitchen environment; their grain will stand straight up when wet to give extra traction. Many US users do not like this and end up sanding the grain down and then oiling the handle instead. It can be an Oval, Octagon or D shaped when viewed from the front/back. These handles are often installed by heating up the tang of the knife and burning the tang into the handle after a pilot ole was drilled into the handle. Many now use a rubbery sealant to seal the tang to prevent water from entering the handle and rusting the tang.

Yo handle: Western handle, often with a metal bolster in the front (or w/o a bolster) with 2 or 3 rivets on the handle. The knife will generally have a full metal tang and will have the shape of European knife handles like a Henckels, Wustoff, Sabatier, etc. Generally heavier than a Wa handle, especially with a metal bolster. Some bolsters may be solid, others are hollow, which helps to reduce the weight. Some Yo handled knives have a partial tang only and have the handle material grooved for the tang to fit in; this is usually on the lower cost knives.

Both handles can be upgraded to custom handles using a variety of woods and other materials, pins, etc. Wa handled knives can have a western shaped handle put on and Western handled knives can be ground down to a narrower wa style tang and converted to a Wa handle.

This is a work in progress, so I decided to make it a sticky and combine a few of my posts to make it easier for people to find!

 Post subject: Re: Intro to Japanese style knives Primer
PostPosted: Sat Nov 08, 2014 8:41 pm 

Joined: Tue Jul 15, 2014 4:52 am
Posts: 213
Location: Auckland, New Zealand
Hi Taz,
great intro to JK's. I only got into JK's about four or five months ago and found it somewhat bewildering. Lots of new terms & concepts and it takes a lot of background work to get your head around all this stuff. I just wish that your primer had been available back then because its a great intro and would have saved a lot of blundering around in the dark.

Thanks for taking the time & making the effort to help put us newbe's on the straight & narrow

Cheers Grant

Just because you're not paranoid doesn't mean they're not going to get you!!
 Post subject: Re: Intro to Japanese style knives Primer
PostPosted: Sat Nov 08, 2014 10:38 pm 
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Joined: Sun Oct 21, 2012 1:34 pm
Posts: 365
Impressive piece of work Tim.
Thanks for taking the time to write this piece. Extremely informative

 Post subject: Re: Intro to Japanese style knives Primer
PostPosted: Wed Nov 12, 2014 4:20 am 
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Joined: Wed Sep 18, 2013 11:21 pm
Posts: 916
Location: Minneapolis, MN
This needs sticky!

 Post subject: Re: Intro to Japanese style knives Primer
PostPosted: Wed Nov 12, 2014 5:38 am 

Joined: Thu Aug 16, 2012 10:03 am
Posts: 359
Great write-up, Tim! Everything you always wanted to know about J-knives, but were afraid to ask.

My blog: Japanese Knife Reviews
 Post subject: Re: Intro to Japanese style knives Primer
PostPosted: Thu Nov 13, 2014 10:06 pm 
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Joined: Wed Sep 26, 2012 8:11 pm
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Location: NE

 Post subject: Re: Intro to Japanese style knives Primer
PostPosted: Fri Nov 14, 2014 11:12 pm 

Joined: Tue Jul 24, 2012 1:28 pm
Posts: 670
Thanks so much for this, very informative and meticulously drafted.


 Post subject: Re: Intro to Japanese style knives Primer
PostPosted: Mon Nov 17, 2014 8:59 am 
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Joined: Sat Nov 15, 2014 3:52 pm
Posts: 21
Just wanted to say thanks for putting the time and effort into this. I read the whole thing a couple times now. There's a lot of info packed in there and it really helped from a vocabulary standpoint. Made reading everything else a lot easier.

 Post subject: Re: Intro to Japanese style knives Primer
PostPosted: Wed Nov 26, 2014 5:11 am 

Joined: Wed Jun 25, 2014 5:25 am
Posts: 104
Great thread. Very informative!

 Post subject: Re: Intro to Japanese style knives Primer
PostPosted: Wed Nov 26, 2014 10:02 pm 

Joined: Fri Nov 21, 2014 7:55 am
Posts: 108
This was very helpful, thanks.

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