Straight Razor Geometry: The Thinnest Edge

The straight razor is the purest geometry exercise in bladesmithing: a blade whose edge angle is fixed by its own proportions, whose grind approaches translucent, and whose performance test is your own face. Nothing else a 2×72 makes is as unforgiving or as satisfying to get right.

The Built-In Angle

A razor hones lying flat on its spine, so spine thickness and blade width set the edge angle permanently. The classical proportion — spine one-quarter of blade width, say a 1/4 inch spine on a 1 inch blade — yields the traditional 7–8 degrees per side. Grind the spine thick or the blade narrow and the owner shaves with a chisel forever. Design the ratio first; everything else follows.

Hollow Grinds and Their Degrees

Razor grinds run from near-wedge (stiff, quiet, forgiving to grind) through quarter and half hollow to full and extra hollow — the singing, flexing extreme ground on progressively smaller wheels. Full hollows want a big contact-wheel pass followed by smaller-wheel finishing near the edge; the classic double-hollow look uses two wheel diameters deliberately. Wedges and near-wedges grind on the platen and are the honest first-razor recommendation: every classical razor assumed a wedge, and faces cannot tell keenness from resonance.

Steel and Hardness

Razor edges finish at apex widths where carbide size is visible reality — fine-grained steel is not optional. The traditional answers remain the best: O1, W2 and 52100 in carbon, AEB-L as the stainless razor steel it was literally invented to be. Hardness runs hard — 60–63 — because the edge is supported by nothing and stropping is the daily maintenance. Big-carbide stainless steels shave like a rasp regardless of sharpening effort.

Points and Details

Round points forgive; square points define (and nick — they are the experienced shaver’s choice); French and barber’s notch points are style with minor function. The tang and monkey-tail balance the open blade on the fingers, the jimps give wet-thumb traction, and the shoulder must leave honing clearance or the first stone session fights the grind. Small blade, dozens of decisions.

Grinding Reality

Razor stock is 1/4 by 1 inch bar ground to near-zero — the most heat-sensitive work a belt grinder does. Post-heat-treat grinding with constant dunking is the norm; the last passes are feather-light. Then honing, which is its own craft: the progression logic in our sharpening guide extended through 8000 grit and a linen-and-leather strop. The 2×72 makes the razor; the stones make the shave.