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My amazing fiancee just got me a Nenox gyuto as a graduation present. (You can't have her, she's mine.) Until now, I've only had Western knives. I understand that I should never use a steel on this beauty. The question is, what regular maintenance can/should I be doing?

I cook every day, frequently more than once, and cutting fresh fruits and vegetables is a major part of that. So this knife will see 10-45 minutes of active use, sometimes very active, every single day.

Korin's website has little to say on the matter. This post suggests that I should not be sharpening more than once a year. I find it hard to believe that the knife will remain as sharp as new for a year. But what else should I be doing? Is there some other honing strategy? Or perhaps a waterstone that is appropriate for frequent use? If so, how often is frequent?

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As I am sure you can tell by looking at it, your Japanese knife is primarily sharpened only on one side. As a result, the cutting edge is angled more steeply. Japaneseknives on Wordpress has some simple pictures illustrating this. This asymmetry is why you can't reliably use a honing rod on it, which relies on swipes to both sides of the edge to keep the blade smooth and free of burs.

The steeper angle makes the blade sharper, but you could say it is a double edged sword that can also make it prone to wearing more rapidly, depending upon how it is treated. As a result, sharpening only once a year may not cut it. There is another page on Korin's website that might be more helpful to you, including an informative video. L'Ohira's Knife Care & Sharpening page has some good tips on the type of kit you might want to use, including 3 grades of water stones, though you may or may not need the course all that much:

  • Arato: A coarse grit stone used mainly for damaged edges and for creating new sharp edges.
  • Nakato: A medium grit stone used for minor repairs and creating sharp edges.
  • Shiage: A fine grit finishing stone.

Much of that information is also covered in the Korin sharpening video.
Also, since the knife is carbon steel, it can rust. Based on your question, it sounds like you probably take good care of your knives anyway, but you should especially make sure you clean this one promptly when dealing with acids.

  • And dry it off immediately after washing. If you're going to be putting it up for a while (eg, going out of town for a few weeks, especially if it's a humid time of the year), a layer of oil might be good, too. – Joe Jul 2 '15 at 0:04
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    Looking at the product description and associated images at mtckitchen.com/p-57-nenox-sd-gyuto.aspx this knife appears to be two-sided 55:45 (dominantly right, but not quite single bevel). In spite of the popularity of the notion that Japanese knives are typically sharpened on one side, that's not necessarily true, and is more typical of knives used in professional kitchens. Gyuto in particular are rarely single-bevel. – JasonTrue Jul 2 '15 at 0:22
  • Thanks, folks! The knife is actually a "stain-resistant" knife, the Nenox G-type, but I am treating it like it's normal carbon steel anyway. And thanks for the video--sounds like very frequent sharpening is totally normal. – David Bruce Borenstein Jul 2 '15 at 1:34
  • @JasonTrue is absolutely right. I did notice that Nenox gyuto knives seem to come in a few different flavors. It looks like this one is 70:30. It is also good to know what a knife is made of. Some Japanese knives are stainless. – JTL Jul 2 '15 at 2:35
  • Agreed, gyutos are the Japanese version of a western chef's knife. They are double beveled, the bevel may not be 50/50, but in this case the g series is actually 70/30 made for a right hander. This can be changed for an additional cost for lefties. Nakiris, sujihikis, and santoku's are also double beveled. Only traditional Japanese knives are single beveled, debas, usubas, yanagis, and other specialty knives. Keep it dry and sharp. I would also mention Jon from Japanese knife imports has youtube videos to help you out. – JG sd Mar 7 '16 at 5:44
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Hone frequently, sharpen periodically

A proper, sharp knife will have a well structured, rigid, and sharp blade bevel (i.e. the very edge of the blade, less than a hair's length across, where the steel comes to a point).

No matter how hard the steel is, the bevel will wear with cutting so it needs to be maintained.

Hone yourself

Honing is the process of drawing the length of the edge along a surface to help maintain its alignment. Knife edges will thin, become ragged, and fold over themselves over time, resulting in a dull edge. By drawing your knife across a honing rod (NOT recommended for 60+ HRC knives) or a leather strop (or balsa, or newspaper on a hard, clean(!!) surface), the rod/strop will help realign your edge so that it is centered across the bevel, remains sharp, and is given proper structural support (triangles are strong!) by the bevel.

Hone often! Honing removes little or no material, and honing a knife before or after use takes just a few seconds and will help keep the edge and reduce the need for frequent sharpening.

Honing is easy to learn (YouTube it) and should be done by knife owners.

Sharpen professionally

Edges will eventually get worn as the steel takes strain from repeated cutting. The edge will get dull through folding, crystalline stress, and microscopic nicking. This cannot be avoided, but honing can reduce the time it takes for the edge to wear.

Once this happens, the blade needs to be sharpened through removing the old steel blade and reshaping it back to its original edge. There are many ways to do this through wetstones, drystones, sanding, grinding, etc.

You can try to do this yourself, but my strong advice (I'm a director of a high end knife company) is to send the knives to a professional sharpener instead. It's hard to get edge angles correct using home equipment, and a properly honed knife doesn't need to be professionally sharpened very often....once every 6 months with frequent use or once every year with less frequent use.

The sharpening period can change dramatically depending on the cutting technique, food products, knife geometry, steel quality, etc. A good way to tell if your knife needs sharpening is if it doesn't feel sharp anymore despite regular honing. That means the edge has worn and it's time to send your baby out for sharpening.

Professional cooks, of course, will go through knives faster because they cook with higher cutting pressure and more frequent use in the kitchen.

Know your bevels

Modern gyutos are NOT always single-beveled. For maintainability and for a global market they are often manufactured with symmetrical or slightly asymmetrical bevels. You should figure out whether your knife has a single, symmetrical, or asymmetrical bevel and write that down somewhere, so that you can let the sharpener know.

  • I would not recommend honing for a Japanese (j) knife. J knives tend to be made from harder/brittle metal, which would be damaged by a honing "steel", metal or ceramic. A leather strop would be a better option, as it burnishes away the burr and realigns the blade. Most J knife makers suggest a water stone to sharpen a knife. Sharpening takes away metal from a knife, but in so doing it makes for a clean/new cutting surface. Most of the Nenox line is at least $200+, not a cheap knife. Euro knives tend to be softer and thicker, honing/steeling is a better option on these knives. – JG sd Mar 7 '16 at 5:35
  • I would respectfully disagree. I work in the knife business and Japanese knives are not necessarily more brittle or harder than western knives. In fact, many $3000+ sujihiki knives are made of more ductile steel to allow for easier maintenance. Water stones are excellent for maintenance if you know how to use then, but the vast majority of folks don't know how to use a stone properly and will end up destroying the edge geometry of the knife in the process. Leather strops are great although I've had mixed results with them.... Maybe because results are very dependent on the stropping compound. – tohster Mar 7 '16 at 6:00
  • I speak only from experience, my sugimoto chukabocho #7, which was my 1st high end J knife years ago. As I had used it for several weeks, then tried to hone it with a sabatier "steel", and severely ruined the edge. I could physically see the edge had chipped and was very jagged afterwards. I also have yet to see any traditionally trained Japanese chef even have a honing steel in their kit. But to each their own, perhaps my technique was wrong when using the steel. But the old adage worked on me, "once bitten, twice shy." I had to bug my sushi chef friend to teach me how to use a stone. – JG sd Mar 7 '16 at 6:16
  • I totally agree that a steel honing rod is usually not a good idea for high end knives... I really prefer ceramic for honing. Also, knives like Nenox or Hattori will tend to use VG-1, 5 or 10 steel which will be harder than your average wustoff/henckels but not necessarily harder than high end knives made from Western steels. Nenox and Shun in particular are infuriating because they advertise high carbon when they are in fact using steel that is not particularly high carbon or, in some cases, performant. It's really great that you took the time to learn how to use water stones! – tohster Mar 7 '16 at 6:23
  • I was lucky that I had a friend that would show me how to sharpen a knife. Now I often use the stone to just make a brief touch up on the knives. This was in the early 90's when J knives were just staring to hit the market. I only had cheap Chinese cleavers and it was a big step for me to go with the Sugi. And then the horror of ruining the edge made me sick to my stomach. Well had to go back to my CCK's, bullet proof, which you could hone on the edge of a ceramic cup. I had to adopt the japanese knife maintenance schedule and tools. Now no problems. Thanks for your response. – JG sd Mar 7 '16 at 6:34

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