From the sharp corners on a slice of sashimi that stands by itself, to the smooth and shinny surface (a.k.a 艶 tsu-ya) of a cut — Cutting properly with a knife does not only make the beautiful food but is also deeply relevant to the flavours the cuts can create.

What is a sharp knife? Its shape, material, manufacturing methods to the ways of knife sharpening all matters. If you aim to achieve the best sharpness of a knife, the first thing is to know the knive types as they are.

Sashimi Knives

Image for post
Image for post

Used from the end of the cutting edge all the way to the tip, Sashimi knives are designed to make slashing cuts. They are praised for their extremely sharp edges and the beautiful cuts they can create. …

When choosing a Japanese kitchen knife, it is inevitable that its steel becomes a part of the consideration. There are a few kinds of steels that are commonly used in modern knife making, and I will cover some that are widely available in stores.

Carbon Steels

The types of carbon steels used in blades are categorized based on their makers. Yasugi factory, owned by Hitachi Metals, Ltd., is located in Shima-ne prefecture, Yasugi city. The steel produced there is not only limited to making the kitchen knives, but also carpenter’s planes, chisels and even high-end knives. …

In Sakai city, there are craftsmen who specialize only in the knife handle making. A good knife should not cause fatigue after prolonged use; this owes to the handle (柄 e) that introduces good balance to the knife.

The Japanese knife handles are usually made of materials like Japanese cypress (檜 or 桧 hinoki), Ebony (黒檀 kokutan) or Japanese yew (櫟 ichi-i). Sakai handle-making craftsmen mostly uses hinoki . Hinoki is light-weight, does not crack easily or rot in water; it also is non-slip when held in hand. These characteristics make hinoki the best fitted material for knife handles.

Placed at one end of the handle, there is either 角巻 Kakumaki, made of buffalo horns, or 口金 Kuchigane, made of metals like copper and brass. In cheaper models, plastic is also used as kakumaki. …

We have covered the terminologies on the different parts of the western and Japanese kitchen knives in a previous article. Let’s talk about the blades.

Single Bevel vs. Double Bevel 片刄と諸刄

Modern kitchen knives can be roughly categorized under either Single-bevelled (片刄 Kataba) knives and Double-bevelled (諸刄 Moroba) knives. When you look at the the cross-section of a blade, if both sides are sharpened at a similar angle it is a double-bevelled knife; if one side of the blade is flat or concave, the opposite side is convex, then you are looking at a single-bevelled knife.

Image for post
Image for post

Knives used by professionals (eg., Sashimi knives, Deba knives, Usuba knives, Hamokiri knives and etc) are almost all single-bevelled ones. When making a cut, the single-bevelled blade does not cut straight and slightly turns in left (for right-handed knives). This feature makes the cut-out part of the ingredient separates easily from the blade so that cuts can be made quickly. Moreover, it is crucial in Japanese cuisine to display the perfectly sliced cross section of the ingredients; single-bevelled knives, capable of closely slicing through the tissue of the ingredients, are the most fitted for this job. …

Let’s get aligned on the terminologies before we continue any further.

Western Knives

Image for post
Image for post

Japanese Knives

A Bit of History

Sakai city of the Osaka prefecture is known for its forged knives (aka. 堺打刃物 sakai-uchi-hamono). It is fair to make the connection between Osaka, the famous “nation’s kitchen”/the food capital of Japan, to Sakai city, where the kitchen knives are produced; however, the history of blacksmithing in Sakai goes way back.

The tomb of Emperor Nintoku is situated in the eastern part of Sakai city. To build such large scale tomb, hoes and plows were produced in large quantities in Sakai city.

When the Portuguese brought guns into Japan in 1543, Sakai city started producing guns during the age of Warring States and quickly became the major supplier in Japan. …

Your knife may have the crazy expensive Japanese steel in its blade, have been sharpened with perfected skills and have been used with extreme care, but you still find it getting dull quickly. Why is that? Let’s look past the knife, and examine what’s underneath it — what cutting board are you using?

An ideal cutting board

  • helps retain the sharp edge of your knife
  • is gentle to your wrist
  • is anti-bacterial
  • should be easy to clean and maintain

Between materials, size, coatings and prices, there are a few trade-offs to consider when finding a good cutting board.

Cutting boards are made of all types of materials today. Since we are aiming for knife edge retention, the harder materials are out of question; avoid glass, ceramic, granite and marble, or you would be spending more time at the whetstones, and the knives’ life span could be shortened due to frequent sharpening. …

Note: This article is not about `rust-lang` but the actual rust that develops on knife blades

Your kitchen knife is very likely made of steel, an alloy that combines Iron, carbon, chromium, nickel and maybe even other metals. Chromium and nickel percentage affects the rust resistance property of the steel. The level of rust resistance is one of the major differences between the modern Western and Japanese kitchen knives and a common worry when some home cooks and professionals look to purchase their first Japanese knives.

Image for post
Image for post

Western chef knives are usually made of stainless steel. Higher chromium and nickel content makes western chef knives effectively resistant to rust. However, this high rust resistance property is no guarantee for a western knife to be free of rust; it is more accurate to interpret “stainless” as “stain less”. …

Regardless of the artificial stones or natural ones, whetstones are usually categorized based on their grits:

  • Rough stone: #200 — #600
  • Medium stone: #800 — #3000
  • Finishing stone: #4000 and up

There are a few other types of stones that you use with the whetstones:

  • A fixer stone: flattens the whetstone
  • A Nagura-toishi: rubs against finishing stones to create a slurry (aka 砥汁) to help with sharpening (this is why the natural stones from Kyoto are called 合砥 awase-do, “awase” meaning “combine”; Nagura is used in combination with natural stone to create the slurry before sharpening.)

The smaller the grit number, the coarse the stone is, and the faster it scrapes away the metal from the blade. Therefore, rough stones are mainly used for repairing edge chip; finishing stones are good for daily maintenance; when the sharp edge cannot be restored by finishing stones alone, use medium stones to reset the bevel. …

Thoughts on the Right Knife Sharpening Angle

Sharpening a knife at the right angle achieves a sharp edge which can last sufficiently long. Finding the right balance between edge sharpness and blade longevity is tricky, though; 2 main parameters contribute to it: the toughness and hardness of the metal, and the angles that the edges are sharpened at.

Image for post
Image for post

Unsurprisingly, the knife craftsmen have figured it all out. Buy your knife from a reputable knife manufacture or craftsman, and you are usually guaranteed a sharp edge. (Most professional Japanese knives require 本刄付け to achieve maximum sharpness. We will cover this later.) Knife manufactures know their steels; some may even have their proprietary recipes for making alloy with undisclosed amount of iron, carbon, chromium and nickel. …


Paul Fangchen Huang

Mobile app developer. Chef-wannabe.

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store