Damascus, Aogami, 14C28N: what a knife's steel really tells you

A knife's spec sheet lists steel names, a number in HRC and often the word "Damascus". That information says a lot, as long as you know what it measures. Here is how to read it, using the steels of our own knives as examples.

Three things make an edge

1. The steel at the core of the blade: it forms the edge.
2. Its hardness, measured in HRC (Rockwell C scale).
3. Heat treatment and geometry: blade thickness and sharpening angle.

The third point hardly ever appears on a spec sheet, yet it often makes the difference between two knives with the same steel. A good clue is the stated sharpening angle. Our knives are sharpened at 15° per side, a fine angle typical of Japanese-style knives.

Hardness, plainly

Harder is therefore not "better" in absolute terms: it is a trade-off between edge life and tolerance to knocks.

Damascus: beautiful, but it doesn't do the cutting

A Damascus blade is made of several layers of steel welded and folded together. Once the blade is acid-etched, layers of different grades reveal the wavy pattern. Most of our knives have 67 layers.

The pattern dresses the blade and protects its core, but it doesn't form the edge. The edge is the core, sandwiched in the middle. A Damascus knife is only as good as its core. Be wary of a spec sheet that talks about the pattern without naming the core steel.

The steels in our knives

10Cr15CoMoV: the all-round stainless

The core of our bunka, our nakiri, our chef's knife, our bread knife, the 3-piece set and the steak knives. A stainless steel with added cobalt and vanadium, often compared to Japanese VG-10. Stated hardness: 60 ± 2 HRC. It takes a good edge, holds it well and stays forgiving to care for.

14Cr14MoVNb: powder steel

The core of our Chinese cleaver, our paring knife and our olive-handled chef's knife. A steel made by powder metallurgy: the carbides, the very hard grains that hold the edge, are finer and more evenly spread. Stated hardness: 62 to 64 HRC. A very lasting edge, a blade to treat gently (no bones).

ZDP-189: the hardest of our steels

The core of our ZDP-189 santoku. A Japanese powder steel very rich in carbon (about 3%) and chromium (about 20%). Stated hardness: 65 to 67 HRC. It is one of the hardest steels used in kitchen knives: the edge stays fine for a very long time, and the steel resists corrosion well. The trade-off: the blade is brittle and sharpens slowly, on fine stones.

12Cr18MoV: the stainless inside the copper Damascus

The core of our tricolour copper Damascus santoku. A stainless steel with 18% chromium, hardened to 60 ± 2 HRC. Around it, the sides mix brass, red copper and stainless: they don't cut, they dress the blade, and they develop a patina over time.

Aogami No.2: Japanese carbon steel

The core of our santoku. "Blue steel" No.2 is a Japanese carbon steel known for taking a remarkably fine edge and for being easy to sharpen. Stated hardness: 62 to 64 HRC. It is not stainless: here it is clad between two layers of stainless steel, but the edge itself can stain if left wet. Over time it develops a grey patina, which is normal and protective.

Sandvik 14C28N: Swedish stainless

The blades of our kitchen shears. A Swedish stainless steel designed for cutlery, combining good edge retention with very good corrosion resistance. At 56-58 HRC it favours toughness: exactly what you want from shears that cut poultry bones.

Which steel for you

• You want the finest edge and don't mind drying your knife: carbon steel (Aogami).
• You want an excellent knife without thinking about it: a quality stainless (10Cr15CoMoV).
• You cut a lot, fast, and want fewer sharpenings: powder steel.

Care, by steel

In every case: no dishwasher, a good board, and a session on the stone now and then. The method is here: sharpening a knife on a whetstone. And to choose the blade shape: santoku, nakiri, bunka or Chinese cleaver.