Japanese Knife Cut 101

I am asked about knife technique by chefs who are anxious to learn how to make sushi, or sashimi. I feel embarrassed about it because sushi is a skill that takes a minimum of 10 years of training before an apprentice can become competent in making sushi.

When asked I always think of a story about a sushi chef I once met. In the 1980’s sushi was much less popular in the west, and was still a novelty. I walked into a sushi counter in Tokyo after the lunch rush, sat down at the counter with my sensei (teacher). It was quiet as we were the only customers. The sushi chef was in his mid 70’s, quiet yet seemed receptive to my questions about his fish. After some nigiri, I asked the chef, “can you tell me, why do you use powdered wasabi” and he began to cry. He explained that he worked for his Dad since he was a teenager, he carried sushi for his Dad for 30 years without directly serving clients. His dad used powdered wasabi to save money and when his Dad passed away he didn’t have the courage to change it after so many years. He was grateful that I recognized he used powdered wasabi and decided to change to fresh.

Many chefs lack the true understanding of knife tradition without consideration of technique. Knife skill is something that most chefs learn in the field and that’s fine when it comes to peeling potatoes. But some chefs learn technique and this video is shows why technique is key: https://mesubim.com/2012/12/14/maximum-skin/

Now imagine the combination of a very sharp knife-technique and now imagine Japan. The history of knife making and its development in Japanese society will help you appreciate the high standard and traditional value in Japanese society. A knife is not just a knife and a kitchen knife /called ho-cho in Japanese/ is a tool to be respected. So where does it all begin? To keep it simple, the Japanese have been experimenting with sword shapes for centuries.

The tradition of knives in Japan is divided into 6 specific time periods:

Jokoto /ancient swords, until around 900 A.D./
Koto /old swords from around 900–1596/
Shinto /new swords 1596–1780/
Shinshinto /new swords 1781–1876/
Gendaito /modern swords 1876–1945/
Shinsakuto /newly made swords 1953–present/

It all begins with the development of single-edged swords and their significance in Japanese society. The kitchen knife developed over centuries by the virtue of Japanese swordsmen and craftsmen realized that a single edge cuts more swiftly. Once you begin to use a traditional Japanese ho-cho for cutting, you begin to understand how they work, and why they work better.

The first Japanese swords were basically variations of the Chinese straight double-edged iron blades however sometime in 700AD, the first Japanese swords began to evolve. The challenge was in the material and the forging but the shape later developed as a means to the end. It was during the last part of the Kamakura that Samurai sword history celebrated one of the most famous and respected sword smiths – the legendary Masamune. A sword isn’t just a sharp blade, it is philosophy.

“A sword should exude an impressive presence when drawn and captivate the eye with its beauty”

Samurai sword history regards Masamune’s swords as some of the most beautifully crafted Katana ever made. Sword legend tells story about Masamune’s sword to illustrates how it possessed a benevolent power. His sword would not harm anything that was innocent or undeserving, even a simple leaf held into the current of a stream passed the blade.

Then in mid 1500’s in Japan the gun was introduced and many sword smiths became gunsmiths and the skills of earlier generations deteriorated. It wasn’t until the great Shogun Hideyoshi unified the country and disarmed the peasantry did Samurai sword history take a turn for the better. Only then, with the Katana being exclusively carried by the privileged Samurai class did the quality of the Japanese sword rise again. Peace followed for 400 years as the gun was rejected and the sword elevated to a fine art of craftsmanship.

In 1876, the Samurai class was officially disbanded and all civilians were ordered to give up carrying swords after encounters with the west made Japan embark on a period of rapid modernization. However, not all the Samurai went quietly, leading to the Satsuma rebellion which lasted for 9 years. This was the last Samurai’s sword history and the remaining sword smiths were forced out of business.

In the 20th century after the world war II, the tradition of swords was finished and swords became collector items. The growing modernized Japanese army was first armed with western style cavalry swords, but quickly switched over to the “gunto sword” a sword based on Japanese design. It was then the shape and design of swords evolved into the modern day kitchen. But in the west a double edged blade is still the blade of choice. However there is no doubt that a single edge is much sharper, performing in a way that doesn’t compare.

Start with a single egde blade and the basic traditional Japanese Knife shapes are YANAGI-BA (a long slicing knife) DE-BA (heavy Knife used for fileting a be-heading fish) and USU-BA (a cleaver shape for vegetables).

The front side of a Japanese knife has a pronounced bevel known as the shinogi line, which is important in the strength of the knife’s tip. The shinogi surface is the flat surface of the blade that runs to the blade’s edge in a single-bevel knife.

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This flat surface allows for a narrow blade angle, resulting in a sharper knife based on the geometry allowing for a razor edge. The development of the knife’s geometry is attributed the shobu katana, made in the 14th century and are reputed to have been a response to the tough leather armour worn by invading Mongol forces.

The issue of the blade is all about “cut and control” and the shape of the front side and back side make all the difference. The flat back (concave) of a knife permits the knife to be handled straight, without any clumsy handing which could result in a severe cut to the user. The knife cut is all about precision and the swiftness requires hand control, practiced strokes and controlled motion. All of this has been developed over centuries via martial arts and tradition.

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When you apply the shape of the knife to a single cut, the handler has more control over the motion and the cut is absolutely more precise. The illustartion below shows the difference in the cut. The doubed edge opens the cut and if the hand angle would move in the downward stroke, an uneven cut would occur. In a sword cut it would leave a victim injured, bleeding profusely with a surface open wound, which is not the objective. In a Japanese cut it is about the swiftness and immediate death.

The difference to the amateur is not necessarily obvious but if you are cutting multiple pieces of food, carrots for example and you wish to have more uniformity, a single edge will leave you with one side that is uniform and the urasuki, the concave surface on the backside of the blade that helps to reduce drag creating smooth cuts. It also prevents foods from sticking to the knife.

The combination of the urasuki and shinogi tip helps pierce foods or flesh (samurai cuts) with very minimal damage which in the kitchen is useful to preserve texture and taste. The uraoshi enhances the blade strength on the edge and aligns any unevenness on back side of the blade running the full length of the knife. Without uraoshi a Japanese knife cannot be sharpened properly or to it’s fullest potential and would be brittle.

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