Blade geometry — the cross-section shape — determines how a scissor cuts hair and which techniques it's suited for. Two scissors made from identical steel can feel completely different if their blades are ground differently.
Convex edge (hamaguri-ba)
The convex edge is the standard of modern professional hair scissors. In Japanese it's called hamaguri-ba (蛤刃, "clamshell blade") because the outside of the blade curves outward in a gentle dome.
Characteristics
- Razor-sharp edge — the edge angle is very acute, so hair is sliced rather than crushed.
- Slide cutting compatible — the smooth curve offers low resistance when sliding along the hair shaft.
- Requires skilled sharpening — the acute angle means convex edges can only be properly serviced by a specialist with the right equipment.
Nearly every Ichiro cutting scissor is built with a convex edge. It handles slide cutting, point cutting, blunt cutting, and most modern techniques without compromise.
Semi-convex edge
Semi-convex sits between a full convex and a traditional bevel. A small flat facet is left near the edge, keeping most of the convex advantage while improving durability.
This geometry suits apprentices and stylists working primarily with wet cutting rather than dry or slide cutting. Semi-convex blades tolerate more use between sharpenings than full convex.
Bevel edge
The bevel edge is the classic scissor geometry: one side flat, the other ground at an angle. It's rarely used in modern professional hair scissors, but still has valid applications:
- Barbering scissors for beard and sideburn trimming
- Some thinning scissors (the flat side serves as a stop)
- Student and entry-level scissors where cost matters more than edge performance
Bevel edges are durable and easy to sharpen, but they don't reach the razor performance of convex blades.
Sword blade
The sword blade is a convex variation where the outer line of the blade curves gently like a Japanese katana rather than running straight. Functionally it's a convex edge, but the line is emphasised for aesthetic and response reasons.
Some Ichiro scissors incorporate sword-blade elements. The performance is equivalent to a standard convex blade, with slightly different visual presence and feel in certain techniques.
Blade geometry fundamentals
Looking at a scissor blade in cross-section, three regions matter:
- Edge — the working surface that actually cuts. Edge angle determines sharpness.
- Belly — the face between the edge and the spine. Curved on convex, flat on bevel.
- Spine — the thick back that provides rigidity. Thicker spines resist flex better.
Edge angle
Professional scissor edge angles typically fall between 40° and 55°. Smaller angles give sharper edges but chip more easily. Ichiro's standard cutting scissors are set at an angle tuned for the balance between initial sharpness and long-term edge retention.
Dry and slide cutting compatibility
If you do a lot of dry cutting or slide cutting, a full convex edge is essential. Bevel and semi-convex edges create more drag along the hair shaft, causing pulling and uneven results.
For wet cutting and blunt-cut techniques only, a semi-convex edge provides enough performance with better durability. The question is how often you do dry or slide work — that determines the geometry you need.
How to tell the difference
Hold the blade up to a light and look at the side profile. A convex edge curves smoothly outward. A bevel edge is straight with a clearly visible angle near the edge. Semi-convex falls in between.
All Ichiro models list their blade type on the specifications page.