The Science of Japanese Knife Sharpness: Edge Geometry and Bevel Angles

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Why Japanese Knives Cut Better: It's Geometry, Not Magic

Source: Pixabay - Free license

Ask a knife enthusiast why Japanese knives are sharp and you'll hear about steel. Shirogami, Aogami, VG-10 — the steel names carry almost mythical status. And steel matters. But it's not the whole story, and it's arguably not even the most important part.

The real secret is geometry. Specifically: the angle, shape, and surface finish of the cutting edge. Two knives made from identical steel but ground to different edge angles will have dramatically different cutting performance. A knife with a 15-degree edge angle cuts with roughly twice the pressure at the contact point as a knife with a 22-degree edge angle, assuming equal force applied. That's physics, not marketing.

Japanese knife-makers understood this centuries before materials science could explain it. The entire Japanese knife design philosophy — from the single-bevel yanagiba to the convex-ground gyuto — is built around minimizing the angle and refining the surface of the cutting edge, using steel that's hard enough to hold those acute geometries without deforming.

This article unpacks the science behind that sharpness. We'll cover edge angles, bevel types, blade cross-sections, the physics of cutting, and what academic research tells us about the relationship between surface finish and perceived sharpness. All sources are Japanese-language — primarily from Tojiro (藤次郎), Sakai Ichimonji Mitsuhide (堺一文字光秀), Masahiro (正広), and published research on the JST (Japan Science and Technology Agency) platform.

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The Physics of Cutting: Pressure, Friction, and Angle

Why Sharper Means Less Force

A knife doesn't cut by being "sharp" in some abstract sense. It cuts by concentrating force onto a tiny contact area, creating enough pressure to exceed the structural strength of whatever you're cutting.

The formula is simple: Pressure = Force ÷ Area

The sharper the edge (smaller contact area at the tip), the more pressure generated per unit of applied force. A razor-thin edge measuring 0.02mm wide concentrates force into a contact area roughly 100 times smaller than a dull edge measuring 2mm wide. Same push from your hand, 100x the pressure at the cutting point.

This is why a sharp Japanese knife glides through a tomato with almost no effort. The edge is so thin that even light pressure creates enough stress to rupture cell walls cleanly. A dull knife, by contrast, crushes and tears — which is why dull-knife tomato cuts are ragged and juicy (the cells burst rather than being separated).

The Role of the Wedge Angle

The blade's cross-section is a wedge. When you push a wedge into food, the food must be pushed apart to let the blade through. The wider the wedge angle, the more the food resists. The narrower the wedge angle, the less resistance.

Tojiro's engineering documentation explains: "The sharpness of a blade is created by the interplay of material performance ('hardness'), blade body structure ('grinding geometry'), and edge performance ('edge angle'). Interestingly, even with high hardness, if the edge angle is obtuse, sharpness will not be excellent. And no matter how acute the edge angle, if hardness is low, the edge will round quickly and sharpness cannot be maintained" (Source: tojiro.net, "切れ味と硬度").

This interdependence — hardness and angle must be optimized together — is the central insight of Japanese knife engineering. German knives use softer steel (HRC 54–56), which can't support acute angles, so they're ground to 20–22 degrees per side. Japanese knives use harder steel (HRC 58–67), which supports angles of 10–15 degrees per side without the edge folding over.

The Pull-Cut Advantage

There's a second geometric principle at work when you slice rather than push straight down. When you draw a blade through food (the pull-cut or hiki-kiri technique), the effective cutting angle is reduced.

Think of it this way: if you push a wedge straight into a piece of fish, the food encounters the full wedge angle. But if you slide the wedge sideways while pushing in, the food encounters a shallower effective angle — the blade enters at an oblique path, making the apparent wedge thinner.

A blogger analyzing the physics of kitchen cutting explains: "When you pull the blade rather than pushing it vertically, the apparent edge angle becomes smaller from the food's perspective, reducing resistance against the food and making it easier to cut" (Source: note.com/10works, "包丁の切れ味を科学する").

This is why sashimi chefs use a yanagiba (a long, thin blade) with a single long pulling stroke — the combination of the acute single-bevel edge AND the pull-cut technique creates the absolute minimum effective cutting angle, yielding the cleanest possible surface on the fish slice.

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Edge Angles: The Numbers That Matter

Measuring Edge Angle

Edge angle is measured as the angle between the blade face and the vertical center line of the blade. It's usually expressed as:

• Per-side angle: The angle on one side (e.g., "15 degrees per side")
• Inclusive angle: The total angle of the V formed by both sides combined (e.g., "30 degrees inclusive")

In Japanese knife culture, angles are almost always discussed per side.

Standard Edge Angles by Knife Type

Knife Type	Edge Style	Per-Side Angle	Inclusive Angle	Notes
Yanagiba	Single-bevel	12–15° (one side)	12–15° effective	Back side is nearly flat
Usuba	Single-bevel	12–15° (one side)	12–15° effective	Back side is flat with urasuki
Deba	Single-bevel	15–20° (one side)	15–20° effective	More obtuse for bone work
Gyuto	Double-bevel	13–16° per side	26–32°	Standard for double-bevel Japanese
Santoku	Double-bevel	13–16° per side	26–32°	Same range as gyuto
Petty	Double-bevel	12–15° per side	24–30°	Can go more acute due to lighter use
German chef's knife	Double-bevel	20–22° per side	40–44°	Much more obtuse
Chinese cleaver	Double-bevel	25–30° per side	50–60°	Built for heavy chopping

The difference between a 15-degree Japanese edge and a 22-degree German edge is enormous in practice. At 15 degrees, the blade tip forms a V that's roughly 30% thinner than at 22 degrees. That means 30% less material spreading the food apart as the blade passes through, which translates directly to less cutting effort and cleaner cuts.

Masahiro's engineering page describes this relationship: "The factors that create sharpness are 'blade angle' and 'blade tip condition' — specifically, the acute angle of the cutting edge and the smoothness of the edge surface" (Source: masahiro-hamono.com, "切れ味について").

The Multi-Stage Bevel System

Professional-grade Japanese knives don't have a single bevel angle. They have a multi-stage system where the blade cross-section changes as you approach the cutting edge:

Stage 1: Primary grind (ji / 地) The main body of the blade, from the spine to the shinogi line. This is the broadest surface and determines the blade's overall thickness profile. Common primary grinds include:

• Flat grind: Straight taper from spine to edge — maximum cutting efficiency, minimum food release
• Convex grind (hamaguri-ba / 蛤刃): A subtle outward curve — "clamshell" shape — that improves food release by pushing food away from the blade face
• Hollow grind: Concave curve — creates a very thin edge but a fragile structure; rare in Japanese kitchen knives

Stage 2: Secondary bevel (kireha / 切刃) The section between the shinogi line and the cutting edge. For single-bevel knives, this IS the main sharpened face. For double-bevel knives, the secondary bevel is the visible "V" shape you can see when looking at the edge head-on.

Stage 3: Micro-bevel (kobazuke / 小刃付け) A tiny additional bevel applied at the very tip of the edge, typically at a slightly more obtuse angle (2–5 degrees wider) than the secondary bevel. This micro-bevel strengthens the cutting tip without noticeably increasing the overall cutting angle. Its width is measured in fractions of a millimeter — typically 0.02–0.2mm (Source: jikko.jp, "包丁の切れ味が悪い原因は小刃にあり").

Sakai Ichimonji Mitsuhide's sharpening guide notes: "A cross-section of a well-sharpened blade tip shows a two-stage structure: the 'blade angle' of approximately 15–20 degrees, followed by the 'edge' at about 25 degrees toward the tip, with a micro-edge stop (koba-dome) of 30–35 degrees in the final 0.02–0.2mm" (Source: ichimonji.co.jp, "包丁の研ぎ方").

This multi-stage system is the engineering compromise that makes Japanese knives work: the primary and secondary bevels keep the overall geometry thin and acute (low cutting resistance), while the micro-bevel reinforces the very tip against chipping (durability). Without the micro-bevel, a 12-degree edge on HRC 62 steel would chip within minutes of use. With it, the same edge lasts weeks of daily cooking.

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Single-Bevel vs. Double-Bevel: Two Philosophies of Cutting

Source: Hocho-Knife.com

Single-Bevel (Kataba / 片刃) Geometry

Single-bevel knives are the crown jewels of Japanese knife engineering. The entire cutting angle is concentrated on one side of the blade — the right side for right-handed knives. The opposite side (the ura / 裏) is nearly flat, with a subtle concavity called urasuki (裏すき).

How the single-bevel cuts differently:

When a single-bevel knife enters food, the beveled side pushes the cut portion away from the blade while the flat side maintains contact with the remaining piece. The result: the piece you're keeping (the one against the flat side) has a perfectly smooth cut surface, while the piece you cut away (the one against the bevel) has a slightly rougher surface.

This asymmetry is why sashimi chefs use single-bevel yanagiba knives. The slice of fish that will be presented to the customer is always on the flat side of the blade — the side with the cleaner cut. The cellular structure of the fish flesh is intact, rather than crushed. This affects both appearance (the surface reflects light more evenly) and taste (intact cells release flavor more slowly on the tongue, creating a cleaner, more lingering taste).

The urasuki concavity:

The flat back of a single-bevel knife isn't truly flat. It has a shallow concavity — like a very gentle spoon shape — ground into it. This urasuki serves two purposes:

1. It creates an air gap between the blade and the food, reducing surface friction and preventing food from sticking to the blade
2. It makes the knife easier to sharpen — you only need to flatten a narrow rim around the edge of the ura, rather than the entire flat surface

Sakai's artisan sharpeners create the urasuki using specialized grinding wheels. The depth and uniformity of the urasuki is one of the markers of quality in a single-bevel knife — a poorly formed urasuki makes the knife harder to sharpen and less effective at food release.

Double-Bevel (Ryoba / 両刃) Geometry

Double-bevel knives are sharpened on both sides, creating a symmetric (or near-symmetric) V-shaped edge. This is the standard for gyuto, santoku, petty, and nakiri — the knives that handle everyday cooking tasks.

Advantages over single-bevel:

• Ambidextrous — works equally well for left- and right-handed cooks
• Cuts straight through food without the lateral deflection that single-bevel knives produce
• Easier to sharpen — the same technique on both sides
• More versatile — handles all food types and cutting motions

Disadvantages:

• The inclusive angle is the sum of both sides (e.g., 15° + 15° = 30° inclusive), which is wider than a single-bevel's effective angle (e.g., 15° on one side with a near-flat back)
• Less precision on delicate tasks like sashimi slicing
• Food release can be worse (no urasuki concavity)

Most home cooks will use double-bevel knives for 95%+ of their cooking. Single-bevel knives are specialist tools for specific Japanese cuisine techniques.

The 70/30 Compromise

Some Japanese knife makers offer a middle ground: asymmetric double-bevel construction. Instead of sharpening both sides equally (50/50), they sharpen the right side at a more acute angle and the left side at a more obtuse angle — typically a 70/30 or 60/40 ratio.

This gives you some of the single-bevel's food-release and cutting-efficiency advantages while maintaining the double-bevel's ambidexterity and ease of sharpening. It's a common configuration on higher-end gyuto and santoku knives from makers like Masahiro and certain Sakai workshops.

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Blade Cross-Sections: The Hidden Architecture

The cross-section of a knife blade — the shape you'd see if you cut the blade in half and looked at the end — determines cutting resistance, food release, and structural strength. Japanese makers have developed distinct cross-sections for different purposes.

Flat Grind (Hira-zukuri / 平造り)

A straight taper from the spine to the edge. The blade forms a simple triangle in cross-section. This is the most efficient cutting geometry — the blade is thin throughout, minimizing the amount of metal that has to push through food.

Used in: Yanagiba, usuba, and some economy gyuto/santoku Pros: Maximum cutting efficiency, easy to sharpen Cons: Poor food release (flat surface creates suction against wet food), less structural strength

Convex Grind (Hamaguri-ba / 蛤刃)

The blade faces curve gently outward, like a clamshell (hamaguri = clam). This is the premium grind for Japanese kitchen knives. The convex curve pushes food away from the blade surface as it passes through, dramatically improving food release. At the same time, the gradual thickness increase from edge to spine provides excellent structural support.

Used in: Premium gyuto, santoku, deba (professional grade) Pros: Excellent food release, strong structure, beautiful cutting feel Cons: Harder to sharpen correctly (you need to follow the convex curve), more expensive to produce

The hamaguri-ba grind is one of the most frequently cited markers of quality in Japanese knife culture. When Japanese knife reviewers describe a blade as having "good nuki" (抜き, release), they're usually describing a well-executed convex grind.

Shinogi-Zukuri (鎬造り)

The classic single-bevel cross-section. The blade has a flat face from the shinogi line (ridge line) to the edge, a flat or slightly convex face from the shinogi to the spine, and the concave urasuki on the back.

Used in: Deba, yanagiba, usuba — all traditional single-bevel knives Pros: The shinogi architecture concentrates grinding on the cutting face only, making sharpening more efficient Cons: Single-handed use only, requires specialized sharpening knowledge

Tojiro's technical documentation describes the shinogi-zukuri cross-section in detail: the shinogi line is the ridge where the cutting bevel meets the blade face, and its precise positioning determines the blade's cutting characteristics and visual proportions (Source: tojiro.net, "刀身の構造").

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The Science of Edge Finish: What Grit Actually Does

Academic Research on Sharpness and Surface Roughness

A study published in the Journal of Cookery Science (日本調理科学会誌) examined the relationship between edge surface roughness and perceived sharpness across knives sharpened by skilled artisans. The researchers measured:

1. Edge-tip roughness (using surface profilometry)
2. Cutting force (measured with a force gauge during standardized food cutting tests)
3. Sensory evaluation (trained panel assessing "sharpness" perception)

The key finding: "A statistically significant negative correlation was observed between blade-tip roughness and sharpness ratings" — meaning smoother edges were consistently perceived as sharper, and required less force to cut through test materials (Source: J-STAGE, "熟練者が研いだ包丁の刃先形状と官能評価との関係").

This validates what Japanese sharpening artisans have practiced for centuries: higher grit finishing produces sharper knives. The progression from a #1000 stone (coarse, ~15μm particle size) to a #3000 stone (~5μm) to a #8000 stone (~1μm) to a natural finishing stone (tennen toishi, sub-micron) isn't aesthetic indulgence — it's creating a measurably smoother edge surface that cuts with less resistance.

What Happens at the Microscopic Level

Under magnification, a knife edge sharpened only on a #1000 stone looks like a saw — a series of tiny teeth and valleys. These teeth catch on food fibers and tear them, producing a rougher cut surface. As you progress to finer stones, the teeth get smaller and the valleys shallower, until at #8000+ grit the edge approaches a continuous smooth surface.

A sharp professional's edge where the micro-bevel has been refined to #6000+ grit will cut through a ripe tomato with almost zero visible juice loss — the blade separates cell walls rather than rupturing cells. A #1000 grit edge on the same steel cuts the same tomato but produces visible juice on the cutting board — cells are being torn open.

The Grit Progression for Japanese Knives

Grit	Particle Size (approx.)	Purpose	When to Use
#220–#400	40–25μm	Repair — removing chips, reshaping damaged edges	Only when damaged
#1000	~15μm	Primary sharpening — establishing the edge angle	Every sharpening session
#3000	~5μm	Intermediate polish — smoothing #1000 scratches	Standard home finishing grit
#6000	~2μm	Fine polish — professional-level edge refinement	Enthusiast finishing
#8000–#12000	1–0.5μm	Mirror polish — maximum theoretical sharpness	Professional/artisan finishing
Natural stone	Sub-micron (varies)	Traditional finishing — adds kasumi (mist) finish	Traditional Japanese sharpening

For home cooks, a #1000/#3000 progression is sufficient for excellent results. The jump from #3000 to #6000 is noticeable but diminishing returns set in rapidly above #6000 for kitchen work.

Our whetstone sharpening guide covers the practical technique for each grit stage.

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How Steel Hardness Enables Acute Geometry

Source: Hocho-Knife.com Source: Pixabay - Free license

The Hardness Floor

Every edge angle has a minimum steel hardness below which the edge will deform under normal use. The relationship is roughly:

Edge Angle (per side)	Minimum HRC for Stability	Typical Use
20–22°	HRC 54–56	German chef's knives
15–18°	HRC 58–60	Standard Japanese double-bevel
12–15°	HRC 60–63	Japanese single-bevel, premium double-bevel
10–12°	HRC 63–67	Razor-class edges, specialty knives

This is why Japanese knife steels are hardened to HRC 58–67 while German steels stay at HRC 54–56. The German approach is "softer steel, obtuse angle, easy to maintain" — the edge bends rather than chips, and can be realigned with a honing steel. The Japanese approach is "harder steel, acute angle, maximum sharpness" — the edge holds its geometry under cutting pressure but will chip (not bend) if abused.

The trade-off is clear: Japanese knives demand more careful use (no twisting, no bone-cutting with thin blades, no lateral force) and proper sharpening (whetstones only), but they reward that care with cutting performance that softer steels physically cannot achieve.

For a complete guide to the steels used in Japanese knives — from budget SK steel to extreme-performance ZDP-189 — see our steel guide and ZDP-189/HAP40 comparison.

Carbon vs. Stainless: The Sharpness Difference

Carbon steel (hagane) takes a marginally sharper edge than stainless steel at equivalent hardness. The reason is microstructure: carbon steel's grain structure is finer and more uniform, which means the edge can be refined to a smoother surface at the microscopic level. Stainless steel contains chromium carbides — hard particles embedded in the steel matrix — that can create tiny irregularities at the edge tip.

In practice, the difference is detectable by trained sushi chefs but negligible for home cooking. A VG-10 stainless edge sharpened to #6000 grit performs within 5–10% of a Shirogami #1 carbon edge sharpened to the same grit, based on cutting force measurements. The carbon edge's advantage shows primarily in:

1. Maximum achievable sharpness (the carbon edge can be refined to a finer apex)
2. Feel during delicate cuts (sashimi slicing, katsuramuki rotary peeling)
3. Aesthetic of the cut surface (smoother cell separation = better light reflection on sashimi)

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Practical Applications: Matching Geometry to Task

Sashimi Slicing: Where Geometry Matters Most

The yanagiba (柳刃) represents the extreme end of Japanese edge geometry. Its single-bevel design, 12–15 degree edge angle, and 240–330mm length are engineered for one specific task: drawing a single, uninterrupted stroke through a block of fish to produce a perfect sashimi slice.

Every aspect of the yanagiba's geometry serves this purpose:

• Long blade: Allows the entire cut to be made in one stroke, without repositioning — each repositioning creates a visible line on the cut surface
• Single bevel: Concentrates the cutting angle on one side, minimizing the effective wedge angle
• Acute angle (12–15°): Minimizes cutting resistance so the blade glides through fish flesh without compressing it
• High grit finish: Produces a microscopically smooth cut surface that reflects light evenly — this is what makes good sashimi "shine" on the plate

For more on the yanagiba and sashimi technique, see our yanagiba guide.

Vegetable Work: Thin Geometry for Clean Cuts

The usuba (薄刃, "thin blade") and nakiri (菜切り, "vegetable cutter") are designed for vegetables, where clean cuts preserve texture and appearance. Both have relatively flat blade profiles that maintain full contact with the cutting board — essential for the push-cut technique used in Japanese vegetable preparation.

The usuba's single-bevel edge is ground to 12–15 degrees and can produce paper-thin cuts (katsuramuki) that are physically impossible with a thicker-angled blade. The nakiri's double-bevel edge is slightly more obtuse (15–16 degrees per side) but more versatile for everyday vegetable tasks.

See our nakiri vs. usuba comparison for the full breakdown.

Bone Work: Where Obtuse Angles Win

The deba (出刃) breaks the "thinner is better" rule. Its single-bevel edge is ground to 15–20 degrees — the most obtuse angle in the Japanese single-bevel family — because it needs to absorb the impact of cutting through fish bones and heads. An edge ground to 12 degrees would chip immediately on bone.

The deba proves that edge geometry must match the task. Acute angles aren't universally better — they're better for clean cutting through soft materials. For impact resistance, you need mass and angle.

Our deba vs. garasuki comparison examines how edge geometry differs between fish and poultry specialist knives.

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Sharpening Angles: Getting It Right at Home

The Two-Coin Method

The most commonly cited technique for maintaining proper sharpening angle in Japanese knife guides is the "coin method": place the knife on the whetstone with the blade at 45 degrees to the stone's length, then raise the spine until it's approximately the height of two stacked 10-yen coins (about 5mm). This produces approximately a 15-degree angle — correct for most Japanese double-bevel knives (Source: ichimonji.co.jp, "洋包丁の研ぎ方").

For single-bevel knives, the beveled side is sharpened by following the existing shinogi line — the angle is already established by the maker, and you maintain it by keeping the shinogi flat on the stone. The back (ura) is pressed flat against the stone and given light strokes to remove the burr.

How to Check Your Edge Angle

Three methods, from simple to precise:

1. The paper test: Hold a sheet of newspaper or printer paper vertically and slice downward. A properly sharpened Japanese knife at 15 degrees per side will cut the paper cleanly without tearing. If it catches or tears, the edge is too obtuse or has burrs.

2. The fingernail test: Gently rest the edge on your thumbnail at a low angle. A sharp edge will "catch" immediately and not slide. A dull edge will skate across the nail.

3. The Sharpie method: Color the edge bevel with a black marker, then make a few strokes on the stone. The marker will be removed where the stone contacts the blade — if the mark is removed evenly across the entire bevel, your angle is correct. If only the top or bottom of the bevel is marked, adjust your angle.

Common Angle Mistakes

Too acute (under 12° per side): The edge will be extremely sharp but chip under normal use. You'll see tiny semicircular chips along the edge after cutting hard vegetables like carrots or daikon.

Too obtuse (over 20° per side): The knife won't feel noticeably sharper after sharpening. Cutting tomatoes and herbs will still feel "mushy" rather than clean.

Inconsistent angle: The most common beginner mistake. If your wrist wobbles during sharpening, you'll round the edge rather than creating a flat bevel. Rounded edges feel dull even when the steel is freshly sharpened. The fix: lock your wrist, move your entire arm, and focus on maintaining the spine height above the stone.

For full step-by-step technique, including video-equivalent descriptions of hand position and stroke patterns, see our sharpening guide.

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Frequently Asked Questions

Does a lower edge angle always mean a sharper knife?

In theory, yes — a lower angle creates a thinner cutting edge that concentrates more pressure per unit area. In practice, there's a limit determined by the steel's hardness and the knife's intended use. Below approximately 10 degrees per side, even high-hardness Japanese steels (HRC 63+) become prone to microchipping during normal kitchen use. The practical optimum for kitchen knives is 12–16 degrees per side — acute enough for excellent cutting performance, obtuse enough to withstand daily food preparation without constant edge maintenance. Razors and scalpels can go below 10 degrees because they cut soft materials (skin, hair) with minimal lateral force.

Why can't I sharpen my Japanese knife with a honing steel?

A honing steel works by bending a deformed edge back into alignment — it doesn't remove metal. This works on soft German steel (HRC 54–56) where the edge folds over rather than breaking. Japanese steel (HRC 58–67) is too hard to fold — it chips instead. Running a hard Japanese edge against a steel rod at speed will create micro-fractures along the edge, making it duller rather than sharper. The correct maintenance tool for Japanese knives is a whetstone, which removes a thin layer of metal to create a fresh, clean edge. Some knife shops sell ceramic honing rods as a compromise — these are gentler than steel rods but still less effective than proper whetstone sharpening.

What's the difference between shinogi height and edge angle?

The shinogi (鎬) is the ridge line where the primary bevel meets the blade face — it's a structural feature of the blade, not directly a sharpening parameter. Edge angle refers to the angle of the cutting edge at the blade tip. You can have the same edge angle with different shinogi heights: a higher shinogi (closer to the spine) creates a wider primary bevel with a more gradual taper, while a lower shinogi creates a narrower bevel with a steeper taper. Higher shinogi generally improves food release and creates a more refined cutting feel, but it also makes the blade thinner (and thus more delicate) at the midpoint.

How often should I sharpen to maintain optimal edge geometry?

For home use with daily cooking, sharpen on a #1000 stone every 2–4 weeks, followed by a few strokes on a #3000 stone to polish. The actual interval depends on: (1) steel hardness — harder steels like VG-10 and Aogami hold their angle longer than softer MoV; (2) cutting board material — soft wood and polyethylene preserve edges, while bamboo and hard plastic accelerate dulling; (3) ingredients — acidic foods (tomatoes, citrus) and hard vegetables (carrots, squash) dull edges faster than soft proteins. You can extend the interval by stropping (running the edge along a leather strop or fine newspaper) between sharpening sessions.

Can I change the factory edge angle on my knife?

Yes, but do it deliberately and understand the trade-offs. Reducing the angle (making it more acute) will increase sharpness but decrease edge durability — you'll need to sharpen more frequently. Increasing the angle (making it more obtuse) will increase durability but decrease cutting performance. If you change the angle, you'll need to remove more metal on the first sharpening to establish the new bevel, then maintain that angle consistently going forward. Most home cooks should stick with the factory angle — manufacturers set it based on the steel's hardness and the knife's intended use. Changing the angle is worthwhile only if you have a specific reason (e.g., adding a micro-bevel for durability on a knife that chips frequently).

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Related Reading

• How to Sharpen a Japanese Knife on a Whetstone: Step-by-Step Method
• Japanese Knife Steel Guide: Shirogami, Aogami, and VG-10 Explained
• ZDP-189 and HAP40: Extreme-Performance Japanese Knife Steels

— The Blade & Steel Team