How to maintain the sharpness of Japanese knives


How to maintain the sharpness of the knife

This is a page of knife sharpening manual. Sharpen your knife by using whetstone.

Types of Wetstone

  1. Natural wetstone
    Found deep in the ground and used since ancient times. Suitable for sharpening knives and other cutting tools. Has smooth sharpening feel, and is the preferred choice of chefs specializing in Japanese cuisine. It’s now hard to buy good quality whetstone due to reduced yield and increased price.
  2. Artificial whetstoneMade of abrasive sand grains solidified by bonding materials. Advancements in grain solidification technologies have enabled development of wear-resistant whetstones with excellent sharpening performance that can be used with various steel materials.


How to use Wetstone

  1. Before use, soak the whetstone in water until it is sufficiently wet. The time required may vary depending on the grain size and fabrication method. Generally, soak a rough whetstone for about 10min and finishing/ceramic whetstones for about 1min.
  2. Keep the surface of the whetstone damp by dripping water on it while sharpening the knife; however, don’t wash off the muddy grains as they provide the most efficient conditions for sharpen the edge. If black shaved metal particulates appear, drip more water onto the surface.
  3. Complete all sharpening (using rough, middle and/or finishing whetstones) in a short period of time. It doesn’t take long, and the longer you grind the edge, the less precise the sharpening angle, resulting in a duller blade.

How to sharpen a knife / For double-edged knife


(1)Firmly grip the handle with one hand and set the blade on the whetstone with the cutting edge facing towards you at an angle of 45 degrees to the vertical axis of the stone (fig. 1).

maintain 2

The back of the blade should be kept at an angle of 10-20 degrees (similar to a pile of 2-3 coins or approx. 3/16 inch / 5mm ) from the surface of the stone (fig. 2)

(2)Carefully place the fingers of your free hand on the center of the blade but take care not touch the cutting edge. Maintain the angle and move the blade in smooth strokes up and down the length of the whetstone.

(3)Sharpen the tip, center section and heel of the blade with 5 to 10 strokes or more until a burr appears in each respective area. (fig. 3).

An 18 cm / 7 inch blade can be divided into three parts for the finishing. Longer or shorter blades require more or less sections.

Always sharpen from tip to heel.

How to sharpen a knife 3

(4)When a burr (“kaeri”,fig. 4) appears on each part of the blade, turn the knife over and sharpen the other side the same way, repeating steps 1-3 (fig. 5).

How to sharpen a knife 4

How to sharpen a knife 5

The “kaeri” should appear on each part of the blade after about 5 or more strokes.

(5)Remove any remaining “kaeri” by lightly dragging each side of the blade across the whetstone (away from the cutting edge). (fig. 6)

(6)After sharpening, remove the grinding paste by rinsing the knife with water, dry it carefully with a towel.

How to sharpen a knife 6

(7)Test the blade by cutting a piece of newspaper, loose leaf or similar paper. A property sharpened knife should be able to easily cut paper (fig. 7). If this appears not satisfactory, repeat steps 1-7.

How to sharpen a knife 7

(8)The blade should now cut paper even more easily.



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