What is a single-edged knife? How to choose one based on the difference between a single-edged knife and a double-edged knife

A single-edged knife that offers the ultimate in sharpness and takes cooking to a new level.

It is the polar opposite of a "double-edged knife" that can do anything; it is a specialist born from the traditions of Japanese cuisine that exists solely to fulfill one purpose perfectly.

In this article, we will carefully explain everything from the basic structure to the roles of typical knives such as deba, yanagiba, and usuba, as well as how to choose the best one to suit your purpose and level.

What is a single-edged knife?

As the name suggests, a single-edged knife is a traditional Japanese knife (wa-bocho) with a blade on only one side of the knife.

It has an asymmetrical cross section resembling the letter "L" and has a slight depression on the back called the " ura-ski ."

Because of this asymmetrical structure, single-edged knives are not good at cutting straight (vertically) like double-edged knives. So why do professionals choose this knife when there are well-balanced double-edged knives available?

This is because, by deliberately abandoning the balance of a single-edged knife's ability to cut straight , it is the ultimate specialist, embodied in Japanese wisdom, able to perfectly perform delicate work that is simply impossible with a double-edged knife .

The three major advantages of single-edged knives

This unique shape creates three overwhelming benefits that double-edged knives do not have.

1. Overwhelming "sharpness of the cutting edge"

• Reason: Unlike a double-edged knife (V-shaped), a single-edged knife (L-shaped) allows the angle of the cutting edge to be approximately half.
  
• Advantages: Because it is as sharp as a razor, it does not crush the cells of the ingredients and creates beautiful, sharp cross sections of sashimi.

2. Realization of thin peeling technology (Katsura peeling)

• Reason: This takes advantage of the fact that the blade cannot cut straight. The single-edged blade has the strength to cut in the direction of the blade due to its structure.
  
• Advantages: When you place the flat, bladeless side (the back side) on the food, the blade will automatically stick to it , allowing you to perform the miraculous feat of "peeling," peeling the food to a consistent, paper-like thickness .

3. Outstanding "detachment"

• Reason: The recess on the back, the " uraski" (back ski ), works.
  
• Advantage: If the back side were completely flat, food would stick to the blade. The recesses in the "back side" create gaps, making it surprisingly easy for cut food to come off the blade.

The difference between single-edged and double-edged knives

While most household knives are double-edged, the single-edged knives used by professional Japanese chefs are specialized knives that are specialized for specific tasks.

This difference is said to have arisen from the differences in their respective food cultures, with Japanese food being about subtraction and Western food being about addition .

Subtractive Japanese cuisine and additive Western cuisine

• Japanese cuisine (subtraction) focuses on the ingredients (fish, vegetables, etc.) as the main focus. The aim is to maximize the flavor of the ingredients themselves using simple seasonings such as dashi and salt. As with sashimi, the single-edged knife was developed as a result of the demand for "ultimate sharpness" to preserve the flavor of the ingredients without destroying their cells.
  
• Western cuisine (addition) involves adding sauces, butter, herbs, etc. to ingredients to create new, complex, and rich flavors. As a result of the demand for "versatility" that allows for efficient cutting of various ingredients, double-edged knives became mainstream.

Comparison table of single-edged and double-edged knives

The main differences between single-edged and double-edged knives can be summarized as follows:

Comparison items	Single-edged knife (professional)	Double-edged knife (all-purpose)
Blade shape	Sharp blade on one side only (asymmetric)	Symmetrical blade
What I'm good at	Specific tasks such as sashimi and peeling	Can cut meat, fish, vegetables and anything
Ease of use	For advanced users (choose your dominant hand)	Safe for beginners (can be used by either hand)
Care	Requires sharpening with a whetstone	Many sharpeners can also be used
Main classification	Japanese knives (unique to Japan)	Western-style knives (global standard)
Main types	Deba knife, Yanagiba knife, Usuba knife, etc.	Santoku knife, chef's knife, paring knife, etc.

Conclusion: Specialist or All-rounder?

• Single-edged knives are recommended for those who are pursuing specific tasks such as sashimi or peeling katsura, or who are pursuing a beautiful finish, and who prioritize sharpness.
• Double-edged knives can be used to cut meat, fish, and vegetables, and are recommended for people who value versatility and ease of use.

It's not a matter of which is better, but rather which one suits your purpose best.

Three typical single-edged knives

The basic cooking of Japanese cuisine is supported by these three types of specialized single-edged knives, each with its own role.

Name of the knife	Main tasks and features
Deba knife	This powerful knife is used to cut off the head of a fish, cut through the bones, and fillet it. It is made much thicker and sturdier than other knives so that the blade will not chip even when it hits the bone . (Some say the name comes from "bucktooth").
Yanagiba knife	Its long, slender shape resembles a willow leaf , and it is also known as a "sashimi knife. " Sashimi is cut in one go to create a beautiful cross section , which is why it has such a long blade.
Thin blade knife	This knife is designed for delicate tasks such as peeling daikon radishes and cutting vegetables into decorative shapes. Although the thickness of the spine (mine) is the same as that of a yanagiba knife, the blade is wider, resulting in a sharper angle at the cutting edge, giving it a "thin cutting edge" as its name suggests. This allows you to cut vegetables without damaging their fibers.

In this way, it is recommended to remember them as "deba" for heavy work, "yanagiba" for beauty, and "usuba" for delicate techniques.

*Note: In addition to the Kanto type (Eastern type) which has a square tip, there is also the Kansai type (Kama-usuha) which has a rounded tip.

How to choose a single-edged knife

Unlike a double-edged Santoku knife, which can be chosen as a "one and all" knife, the purpose of choosing a single-edged knife is very important: "What do you want to do with it?" Follow the steps below to clarify your needs.

Step 1: [Most important] Choose the type based on your purpose

Single-edged knives are specialists that are specialized for specific tasks. The type of knife you should choose depends on what ingredients you want to use and what task you want to perform.

<Differences in traditional Japanese cuisine>

• The purpose is to "cut" fish → Deba knife
• The purpose is to cut sashimi beautifully → Yanagiba knife
• For delicate work with vegetables → Thin blade knife

<Use across genres>

Recently, single-edged knives are increasingly being chosen across the boundaries between Japanese and Western cuisine. For example, Western chefs use yanagiba knives to slice carpaccio and roast beef, or deba knives to fillet fish. The first step is to consider how you would like to utilize the sharpness of a single-edged knife in your own field (genre) of expertise.

Step 2: Select the "Material"

The material is determined by how you plan to maintain the knife. The main materials for single-edged knives are steel and stainless steel.

Steel:

• Features: Contains a high amount of carbon, giving it outstanding sharpness, durability, and ease of sharpening.
• Recommended for: People who prioritize sharpness, and advanced users who are particular about cooking and enjoy maintaining their knives by sharpening them.
• Caution: Because it is prone to rust, careful maintenance is required, such as wiping off any moisture immediately after use.

stainless:

• Features: The biggest advantage is that it is rust-resistant and very easy to maintain on a daily basis.
• Recommended for: Those who want sharpness but also prioritize ease of use, and beginners who are not confident in maintenance.
• Note: In the past, it was said to be inferior to steel, but recently products that combine sharpness and ease of use, such as "composite materials" that use steel as the core material, have become mainstream.

Step 3: Select the blade length

Choose the optimal length based on the size of the ingredients you will be using, the work space in your kitchen, and the storage space. If it is too long, it will be difficult to hold on the work surface, and if it is too short, it may be inconvenient to cut the ingredients in one go.

The general guidelines for households are as follows:

• For sashimi knives (yanagiba) : Ideally, a long blade length (e.g. 240mm to 270mm) is ideal to cut the sashimi beautifully in one go, but if your kitchen space is limited, choosing a slightly shorter blade length of around 210mm is easier to handle and more practical.
• For Deba knives : If you are mainly cutting small fish such as horse mackerel, a shorter knife (e.g. 120mm) is suitable, but if you are also cutting sea bream or yellowtail , a standard to longer knife (e.g. 150mm to 180mm) is suitable.
• For thin blade knives : Since these are knives used for cutting vegetables, it is important to balance them with the size of the cutting board. For home use, the standard length is 165mm to 180mm , which is a length that makes it easy to do tasks such as peeling knives.
• Single-edged Gyuto : Like double-edged Gyuto, it is used as an all-purpose knife. Depending on the size of your kitchen, a size between 210mm and 240mm is the most convenient size for home use and provides a good balance of work efficiency.

Step 4: [Must Check] Choose your "dominant hand"

This is an important point to check when choosing a single-edged knife that you should never make a mistake in .

Because single-edged knives have an asymmetrical structure, there are always separate right-handed and left-handed versions . If you choose one based on the way you would choose a regular double-edged knife, you won't be able to use it properly. Most knives on the market are for right-handed people, so if you're left-handed, make sure it's for left-handed people before purchasing.

Step 5: Choose a handle based on the "center of gravity" and "ease of maintenance"

Most single-edged knives are "Japanese knives (with a concave handle)," and their structure affects ease of use (center of gravity) and maintenance.

① Japanese knife (sashi-handle) type

• Features: A traditional structure with a thin metal core (core) extending from the blade inserted about halfway into the wooden handle.
• Center of gravity: The center of gravity tends to be at the tip of the blade (the blade is heavy), which makes it easier to control delicately with your fingertips.
• Caution: Due to its structure, moisture may reach the core and cause rust, so it is designed to require future replacement of the handle.

② Western-style knife (rivet handle) type

• Characteristics: Found in some kitchen knives, such as single-edged chef's knives. The core extends all the way to the handle and is secured with rivets for a sturdy structure.
• Center of gravity: The center of gravity tends to be closer to the handlebars (butt-heavy).
• Advantages: Handles with a "kuchigane" (ferrule) are less likely to allow water to get inside the handle, and tend to be more durable than the sashi-style handles of Japanese knives.

Rather than choosing which is better, it's best to choose based on your own "familiarity" and preferred "weight balance."

How to care for a single-edged knife

The extraordinary sharpness of a single-edged knife can only be maintained with proper maintenance.

1. [Most Important] Do not use simple sharpeners.

Never use the simple household sharpeners that involve inserting the blade into a groove and pulling it.

Single-edged knives have a very delicate structure, with an asymmetrical blade and a back bevel. Using a sharpener will completely destroy this structure, which is like a life force, and the knife will never regain its original sharpness.

2. A whetstone is essential to maintain sharpness

Maintaining a single-edged knife using a whetstone is essential. Learning how to sharpen a single-edged knife with a whetstone is one of the joys of mastering it.

3. Daily maintenance: Rust and moisture control

Steel knives are particularly susceptible to rust, so wash them immediately with fresh water after use and wipe off all moisture with a dry cloth. It is strictly forbidden to leave them wet.

In particular, if moisture gets into the "sashi-gaki" (handle) of a Japanese knife at the base of the handle, it can cause the inside to rust, so be sure to wipe off any moisture at the base as well.

Frequently Asked Questions (FAQ)

Q. Why can't I cut straight with a single-edged knife?

A. That's because single-edged knives have an asymmetrical structure. Because the cross section is shaped like the letter "L", when you apply force straight down, the blade naturally cuts into the side where the blade is (the right side for right-handed knives), resulting in an angled cut. This is a characteristic of single-edged knives and is not a defect.

Q. How can I make straight cuts with a single-edged knife?

A. To cut straight (vertically) with a single-edged knife, you need to consciously control the knife to counteract its tendency to "dig in." For right-handed knife cutters, the blade will naturally dig in to the right side. To prevent this, professionals adjust the blade to descend vertically by either "tilting the knife itself slightly to the left" or "cutting with enough force to push the tip of the blade to the left." This is a feeling that does not exist with a double-edged knife, and is an advanced technique that requires practice.

Q. Can I cut sashimi with a deba knife?

A. No, we do not recommend it. Deba knives have very thick and heavy blades to cut through fish bones. With a blade this thick, it is not possible to cut thin and cleanly like sashimi, as the flesh will be crushed. For sashimi, a yanagiba knife (sashimi knife) is used, which has a thin, flexible, and long blade, and is cut in one stroke to create a beautiful cross section.

Q. Is it true that a single-edged chef's knife is not recommended for beginners?

A. No, we do not recommend it. If you use it in the same way as a double-edged knife, the asymmetrical structure of the single-edged knife (asymmetric left and right) will cause the blade to dig into the food, making it very difficult to cut straight. This is a knife for advanced users, and should be considered only after you have mastered the use of a double-edged chef's knife.

Q. Where can I find left-handed versions?

A. Generally, you can find them at knife specialty stores with a wide selection or online shops. Due to the structure of single-edged knives, right-handed and left-handed knives are completely different. If the item is out of stock, it may be made to order, so be sure to confirm that it is "left-handed" before purchasing.

Q.Do "Japanese knife" and "single-edged knife" mean the same thing?

A. It's close, but not strictly speaking. "Japanese knives" is a general term for traditional Japanese knives, and most of them (such as deba, yanagiba, and usuba) are single-edged. However, there are some knives, such as the "wagyuto," that have a Japanese handle (a sashi-gaki handle) but a double-edged blade.

summary

The four most important points about single-edged knives explained in this article can be summarized as follows:

• Single-edged knives are specialized knives for specific tasks
• It features an asymmetrical structure and a "back ski"
• The most important factors when choosing are "purpose" and "dominant hand"
• Maintenance requires a whetstone, no sharpeners allowed

Single-edged knives are "specialists" that have evolved to perfectly fulfill specific purposes within the Japanese cuisine culture of "bringing out the flavor of ingredients." Their roles are clear, such as the "deba" for heavy work, the "yanagiba" for beauty, and the "usuba" for delicate techniques.

Of course, due to its high level of specialization, it requires knowledge and skill (especially maintenance with a whetstone) to use it effectively.

However, a single-edged knife is not just a cutting tool. It is a partner that allows you to seriously engage with ingredients and pursue precision in cooking and the beauty of the finished product.

Using the selection methods introduced in this article (purpose, material, blade length, dominant hand), we hope you will find your "first knife" that will take your cooking to a new level.