How to Sharpen a Knife Like a World-Class Sushi Chef

Stop settling for dull knives.


A dull knife is a useless tool. While electric sharpeners offer convenience, speed and power, manual sharpening stones, called whetstones, offer greater control over the angle of an edge. They’ve been used for centuries and are gentler on blades, but they also come with a learning curve.

“There’s no real end to learning how to sharpen knives because there’s always something more to improve on,” explains Vincent Lau, a sharpener at Korin, an early importer of Japanese knives to the U.S., who has trained under company founder Chiharu Sugai for eight years. That shouldn’t be a deterrent, however. Basic whetstone sharpening is simply a matter of finding the proper angle.

Sharpening Essentials

Whetstone Gear for Beginners


Chef’s Knife Learn More
1000/6000-grit Two-Sided Sharpening Stone by Mizuyama $73
Sharpening Stone Base $35
Sharpening Stone Fixer $20
Nagura $10

Know your stones: Whetstones are made with a range of materials, from ceramics to synthetics, or a cement-like conglomerate of finely ground stone. All whetstones are categorized according to grit, or coarseness. Rough stones have a lower grit count and are the first step in sharpening a particularly dull or chipped blade. Medium whetstones hover in the 800- to 2,000-grit range and are most often the first step in sharpening a knife. Whetstones with a grit count of 3,000 or above are referred to as finishing stones, and are used for refining and polishing.

The price of a whetstone is most often indicative of its quality, which directly correlates to how hard the stone is. “The more expensive stone, typically, is comprised of a harder material, which is efficient at grinding metal off of a good-quality knife,” Lau says. “It allows you to sharpen quicker [and] it allows you to sharpen a very high-quality knife, whereas a cheaper stone may not create a good edge if a knife is made from a very hard metal.” A well-made whetstone should cost $60 to $70.

Double-sided stones, with a medium grit on one side and finishing stone on the other, are popular among beginner sharpeners and convenient for home use. Lau recommends the Mizuyama two-sided whetstone ($73), with 1,000- and 6,000-grit sides, for beginners. “The stone itself is very high quality, really geared toward high-quality knives, so you can pretty much sharpen any metal with this one.”

Keep it level: Whetstones wear down over time, but it’s important to keep the surface as flat as possible to ensure even sharpening. A stone fixer ($20) can be used to smooth the whetstone’s surface.


Prep your stone: To adequately lubricate the stone, rough and medium whetstones should be soaked in water for 20 to 30 minutes, or until air bubbles stop rising, before use. Finishing stones should not be soaked, as they are prone to cracking. Instead, sluice a fine-grit stone with water and use a nagura, or dressing stone, to create a slurry of silt for improved polishing. Once ready, place a sharpening base on a flat surface and fit the whetstone on top of it.

Nail the technique: Begin by positioning the knife with the edge facing up. Place your thumb on the spine and your index finger on the heel. Hold the knife so that the blade forms a straight line with the rest of your arm. Position the knife so that the bevel of the edge is flat against the whetstone. Note that this angle will be different for every knife; it’s a matter of feeling it out.

Place the index and middle finger of your other hand on the tip of the blade. Apply pressure and swipe the blade down in a pulling motion. Release pressure, and move the knife back up to your starting point. Apply pressure only when stroking down; otherwise, you’ll risk cutting into the stone. Repeat the up-and-down swiping motion; with each swipe, inch your two fingers along the blade, in the direction of the heel. When you’ve reached the heel of the blade, use the index finger of the opposite hand (which should already be placed on the heel) for extra support. Run a finger along the opposite edge of the knife. There should be a slight ridge, or burr.

Repeat the process on the opposite side of the blade, this time with the edge facing down, index finger on the spine and thumb on the heel. Because the direction of the edge has changed, you’ll now be applying pressure when swiping up. To ensure consistent pressure, avoid switching hands. Grind the full length of the blade along the whetstone, and check for a burr.

Pace is important, Lau notes. “I see people try to sharpen too quickly. They try to move the knife very fast, and that’s not necessary. The most important thing is consistency — you want to maintain the angle.”

Work from coarse to fine: A low-grit stone is typically only used if a blade is chipped or significantly dulled. In most cases, it’s safe to start with a medium whetstone and end with a finishing stone, using less pressure when working with the latter, as the goal is simply to polish and remove the burr along the blade’s edge.

To ensure that the burr has been ground away after using the finishing stone, pinch the edge between your thumb and index finger and pull your hand away, as if plucking a thread from the blade. Repeat the motion along the full length of the blade and re-sharpen on the finishing stone if any bumps remain.

Keep count: If you’re sharpening a chef’s knife, or any Western-style kitchen knife, be sure to count your strokes. To keep the edge even, both sides of the blade should be ground symmetrically.

Test your edge: A well-sharpened blade should slice through a sheet of printer paper (or, even better, magazine or newsprint) without catching, and cut through a tomato without puckering the skin.

Dry the stone: Coarse and medium whetstones can be left in water to be ready to use at a moment’s notice, or air dried and stored away. Finishing stones should always be air dried, as they will crack if saturated. Avoid wrapping a whetstone in a towel, Lau says, as that can cause the stone to grow moldy.

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