Why Is My Knife Chipping?

Chips are almost always environmental. Work through these in order and the cause will usually be obvious by number three.

The commonest cause, and the one people least suspect. Glass and stone boards are obviously wrong. Bamboo is the hidden one: it is a grass with high silica content and it is considerably harder than the hardwoods it resembles. Composite and some plastic boards are harder than they look too.

Test: press a thumbnail into the board. If it leaves no mark at all, the board is harder than your edge. What to use instead.

An edge needs steel behind it. Below roughly 12 degrees per side on a kitchen knife, there is not enough metal supporting the apex and it fractures under normal load rather than flexing.

This catches people who read that Japanese knives are sharpened at 15 degrees and then aim lower to get sharper. It also catches people whose angle wanders — a stroke that drops to 10 degrees near the tip leaves that section fragile.

Test: color the bevel with a marker and make three passes at the angle you normally use. If the ink comes off only at the very apex, you are too steep; if the bevel looks very wide and shallow, you are too acute. The angle guide.

Carbide pull-throughs scrape steel out rather than abrading it, and they force the edge to their own fixed angle regardless of what the knife was ground at. On hard steel the result is micro-chipping along the entire edge.

Test: look along the edge under a bright light. Damage concentrated at a few points is impact. Fine, even roughness along the whole length is a pull-through. What they do.

A knife rattling loose in a drawer meets a can opener, a peeler and the drawer runner every time it opens. This accounts for a large share of chipped tips specifically — the tip is the thinnest, least supported part of the blade.

Test: damage concentrated at the tip, appearing between uses rather than during them. A sheath costs almost nothing. Storage guide.

A thin blade is strong in compression along its length and weak in torsion. Levering a squash apart, prying a chicken joint, or twisting to free the knife from a dense root all apply forces the geometry was never designed for.

Test: a single larger chip, usually mid-blade, appearing after a specific memorable cut.

Bone, joints, frozen food, and — occasionally — a stone in a bag of dried beans or grit on unwashed root vegetables.

Test: a chip that appeared during a cut you can remember.

Harder steel chips more readily. That is not a defect, it is the trade you accepted when you bought hardness.

If your knife is 63 HRC with a sub-12-degree factory edge, the tolerance for all six causes above is much smaller. VG-10 against SG2.

1. Assess the depth. Look along the edge under a bright light. Micro-chipping looks like fine roughness; a real chip is a visible notch.
2. Grind on a coarse stone. 400 grit or lower, at your normal angle, until the notch is gone along the full length. This removes real steel — be patient and check often.
3. Re-establish at 1,000 grit, then finish and strop as normal. Full sequence.
4. Fix the cause first. Otherwise you will be back here in a fortnight having spent another millimeter of blade.