Inner Hollow / Concave
Edge typesIllustrations are navigation markers, not technical evidence. They do not establish exact geometry, material identity, finish or coating identity and properties, adjustment settings, coating colour, hair classification, tooth pattern or removal rate, mechanism, fit, diagnosis, origin, performance, or result.
Description
The concave or hollow-ground interior reduces blade contact area for smoother action and less drag. Learn how inner hollowing affects scissor performance and feel.
Inner Hollow / Concave
Quick look
- Friction control: Hollow grinding removes metal behind the edge so blades touch lightly and close without crushing hair.1,2
- Edge support: A polished ride line keeps the razor edge aligned and extends service life.1,2
- Service needs: Poor sharpening that flattens the hollow destroys glide and the shear’s bite.1,2
Why stylists pick it
Every premium convex or semi-convex shear relies on the inner hollow. By carving relief into the interior face, manufacturers ensure only the edge and ride line make contact, which produces the smooth, silent close stylists associate with high-end tools.1,2
Trade-offs
The inner hollow is a feature of construction, not of the cutting edge geometry itself — the convex or semi-convex edge still does the actual cutting. Where the hollow earns its keep is in reducing drag: less metal-on-metal contact means the blade glides rather than scrapes. The price of that glide is sensitivity to sharpening. A technician who grinds on a flat wheel will fill the hollow and restore surface contact, undoing the advantage entirely. Depth of hollow also varies between manufacturers — a deeper grind feels lighter but leaves a thinner wall of steel, which can flex under pressure during dense blunt cuts.1,2
Technique map
- Any technique that depends on low resistance-dry detailing, slide work, and point cutting.1
- Supporting daily salon rotations by keeping the edge sharp longer between services.2
- Ensuring tight, even closure during precision barbering work.2
Usage notes
- Perform regular tension tests; a loose pivot lets the hollowed blades chatter and nick the ride line.2
- Keep the interior spotless-lint or hardened product defeats the low-friction design.1
- Avoid tapping blades together or laying them open; protect the ride line from flat surfaces.2
Maintenance
- Choose sharpeners who re-establish the ride line and hollow on specialty stones rather than bench grinders.1,2
- Oil sparingly along the ride line so the edge closes smoothly without attracting debris.1
- Schedule service before the edge feels dull; excessive force can overheat and warp the hollow.2
Sources
- Japan Scissors - Hair Scissor Blade Shape and Edges Guide
- Dark Stag - Convex vs. Bevelled vs. Serrated
See Also
Sources Reviewed
1 scoped source behind this entry- Secondary Japan Scissors Australia (direct sales)
Frequently Asked Questions
3 answers you can open one at a timeWhat is the ride line, and what happens when it wears?
The ride line is the narrow raised strip along the interior face of the blade that makes contact with the opposing blade during the close. On a hollow-ground scissor, only this strip and the cutting edge touch — the hollowed interior keeps everything else clear. When the ride line wears down through use or improper sharpening, the blades begin making full-face contact. Friction rises sharply, the close becomes heavy, and the edge dulls faster because more metal surface is dragging instead of cutting.
Is the inner hollow a feature of all professional scissors or only Japanese ones?
Hollow grinding appears on both Japanese convex and European beveled scissors, though the depth and profile differ. Japanese convex edges use a deep, smooth hollow that gives the blade its characteristic lightweight close. European beveled scissors use a shallower hollow, sometimes called a flat grind with relief, that still reduces contact area without eliminating the secondary bevel. Budget scissors often have no interior hollowing at all — both faces are flat, which makes the close noticeably heavier and dulls the edge faster.
Can a damaged inner hollow be repaired, or does it mean replacing the scissor?
Minor wear to the ride line can be corrected by a sharpener who re-establishes the hollow on specialist stones. Severe damage — deep scratches, pitting, or a hollow that has been polished completely flat — is harder to reverse. Polishing the hollow flat removes the geometry that makes low-friction cutting possible, and re-grinding the hollow requires removing significant material. The economics depend on the scissor’s value; on a pair worth several hundred dollars, a skilled togishi may restore the hollow. On a budget shear, replacement is often the practical choice.
Comments & questions
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