A lame, a razor and a kitchen knife cut dough differently because of drag

The theory of scoring tools is well covered elsewhere. This is about the version you meet in practice.

Why blade thickness dominates

Proved dough is soft, sticky and inflated, and anything pushed into it displaces material rather than parting it. A very thin blade separates the surface with minimal displacement, so the cut closes cleanly behind it.

A thick blade wedges the dough apart, dragging the surface skin and releasing gas from the cells it disturbs. That drag is what turns an intended clean line into a torn, ragged trench with dough clinging to either side of it. This is the entire argument for a razor blade over even a very sharp kitchen knife.

What a lame adds

A lame is a handle that holds a replaceable razor blade, usually with a slight curve along its length. The handle gives control over angle and depth, which is difficult with a bare blade between the fingers.

The curve lets the blade cut under the surface at a shallow angle rather than straight down. That undercut creates a flap that lifts during oven spring, which is what bakers call an ear. A straight blade held vertically gives a cut that opens symmetrically on both sides instead, which is what decorative patterns need.

Angle and depth

A shallow angle produces a flap and a dramatic opening; a vertical cut produces a split that opens evenly on both sides. Depth matters less than most bakers expect, and a cut far too deep releases gas rather than directing it. Too shallow, and the crust sets before the dough can open there, so it bursts somewhere else instead.

In the tin, the right depth is enough to break the surface skin decisively without cutting into the body of the loaf. Practising on a spare dough and observing where it opened teaches this faster than any description.

Sharpness and stickiness

Blades dull quickly against dough and flour, and a dull razor drags exactly like a thick blade does. Replaceable blades exist because sharpening is impractical, so change them more often than feels necessary. Wetting the blade reduces sticking on very wet doughs, though it needs repeating between cuts and washes off the flour dusting.

A light dusting of flour on the loaf surface also reduces drag and makes the cut more visible.

Cold dough from a retard cuts far more cleanly than warm dough, which is a practical argument for retarding.

Alternatives that work

Scissors make clean cuts in soft doughs and are traditional for certain shapes, since they do not drag along a line. A very sharp thin-bladed knife works adequately on firm doughs and poorly on slack ones.

A serrated knife tears rather than cuts and should be kept for slicing the loaf afterwards. Some breads are not scored at all and are left to open naturally where the crust is weakest. Others are dusted or stencilled, which is decoration rather than direction and does nothing structural.

Proving times are written for a warm kitchen, and yours may not be one.

Storing a blade safely

A bare razor blade in a drawer is a genuine hazard and the main reason for using a handled tool. Blades should be stored in their dispenser and disposed of in a sealed container rather than loose in a bin. Keeping the tool dry prevents rust, which dulls a blade far faster than cutting dough does.

Cleaning dough off the blade immediately is far easier than removing it once it has dried hard around the edge. A single lame with a supply of blades is a small purchase that visibly improves loaves from the first bake.

The takeaway

Use the thinnest blade you can, keep it fresh, and let the angle rather than the depth decide how the loaf opens.

Bake it badly once on purpose. The failure teaches more than the photograph.