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Sharpening Glestain and Masahiro Knives: A Geometry-Based Approach
Glestain and Masahiro knives require a different sharpening technique than conventional kitchen knives due to their unique blade geometry. This article explains how these knives are constructed, why that construction affects sharpening, and how to sharpen them correctly while preserving their intended performance.
Blade Geometry Overview
Standard Knife Geometry
Most kitchen knives use a symmetrical blade shape, similar to an isosceles triangle:
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Both sides descend from the spine at the same angle
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Blade geometry is identical on each side
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Edge bevels may vary, but the blade shape does not
This symmetry allows both sides of the edge to be sharpened at the same angle.
Glestain and Masahiro Geometry
Glestain and knives use an asymmetrical blade shape, closer to a right triangle:
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One side of the blade (typically the left on right-handed knives) meets the spine at approximately 90 degrees
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The opposite side slopes gradually from the spine to the edge
This geometry improves cutting efficiency and food release by encouraging food to move away from the blade during use.
Why This Geometry Changes Sharpening
Because each side of the blade descends from the spine at a different angle, sharpening both sides of the edge identically would distort the cutting geometry. Never use a pull-through sharpener on these knives, as it will force a 50/50 edge and ruin the asymmetrical grind.
To preserve the blade shape, these knives use a compound bevel, where each side of the edge is sharpened at a different angle using whetstones.
Factory Edge Configuration
From the factory, Glestain and Masahiro knives are typically sharpened with an 80/20 ratio:
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80% of the edge formed on the primary blade face (the Right side on a right-handed knife).
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20% of the edge formed on the back side (the Left side on a right-handed knife).
Note: Glestain knives feature signature scallops (dimples) on the primary face, while Masahiro knives are perfectly smooth. Despite this visual difference, the 80/20 sharpening geometry is identical for both.
Sharpening Guidelines
Pro-Tip: The Sharpie Trick
To easily find your factory angles, color the very edge of the blade with a permanent marker. Take a light pass on your stone—if the ink is removed cleanly, you have matched the correct angle.
Blade Face (Right Side)
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Angle: 16–18 degrees
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Purpose: Establishes primary cutting geometry
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Method:
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Spend the majority of sharpening time on this side
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Sharpen until a consistent burr forms along the entire edge (you will feel this tiny burr catching your thumb on the opposite side)
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Note for Glestain: The scallops do not affect edge formation and can be ignored during sharpening.
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Back Side (Left Side)
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Angle: Approximately 22 degrees
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Purpose: Removes burr and supports edge
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Method:
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Use light pressure
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Make only a few passes
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Avoid over-sharpening
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(Note: Left-handed models reverse this geometry. Identify your primary face before sharpening).
Key Principles to Maintain Performance
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Do not use pull-through sharpeners
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Do not sharpen both sides at the same angle
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Do not split sharpening time evenly between sides
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Preserve the asymmetrical (80/20) edge ratio
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Let blade geometry dictate sharpening angles
When to Use a Honing Rod vs. a Sharpening Stone
For regular maintenance, light honing can help realign the edge between sharpening sessions. When the knife no longer responds to honing, use quality sharpening stones to restore the bevel. Waterstones are usually the best choice for controlled edge work on these knives.
If you are new to compound bevel sharpening, start slowly and remove as little steel as possible. The goal is not to create a new edge geometry, but to maintain the one the knife was designed to use.
Recommended Sharpening Tools
For maintaining Glestain and Masahiro knives, browse our selection of sharpening stones, Naniwa sharpening stones, and Masahiro whetstones. For more background on this style of edge, see our guide to how to sharpen compound bevel knives.
Summary
Glestain and Masahiro knives are designed around an asymmetrical, right-triangle blade shape that delivers exceptional cutting efficiency and food release. Maintaining this geometry requires a compound bevel with different sharpening angles on each side of the blade.
By sharpening the primary blade face at a lower angle, the back side at a higher angle, and maintaining an asymmetrical edge ratio, you preserve the knife’s intended performance and longevity.
