How to read a kitchen knife

Hardness is a choice about your own behaviour

Steel hardness is measured on the Rockwell C scale and the useful range for kitchen knives runs from about 55 to about 64. Robert Welch state theirs plainly: German stainless hardened to Rockwell 56. A Japanese blade built around Aogami Super sits several points higher.

Those few points are the whole personality of the knife. Softer steel rolls rather than chips, comes back with ten seconds on a steel, and forgives being dropped in a sink, scraped across a board edge-first and put away damp. Harder steel takes an edge that genuinely feels different to use, holds it for weeks rather than days, and will chip if it meets a bone, a frozen edge or a stone worktop.

So the question is not which is better. It is whether you are the sort of cook who sharpens things. If you are not, a 56 will serve you better than a 64 and you will be happier.

• Robert Welch harden their German stainless to Rockwell 56. Robert Welch
• Blenheim build on Aogami Super, which sharpens keenly and holds an edge. Blenheim Forge

The steel's name tells you more than any adjective

A page that says high carbon German steel has told you almost nothing. A page that names the alloy has told you everything, because the designation is public and specific. Robert Welch name 1.4116; Sous Chef name a VG10 core on the Senzo range and AUS10 on another.

You do not need to memorise them. You need to notice whether the maker gives one, because a maker who names the steel is a maker who knows what they bought, and the ones who describe the steel in adjectives are usually describing somebody else's.

• The alloy is named as 1.4116. Robert Welch
• Sous Chef name a VG10 core on the Senzo range. Sous Chef
• Another is forged from AUS10 around a thick core. Sous Chef

Clad construction is why a carbon knife is usable at all

The best edges are carbon steel, and carbon steel rusts if you look at it wrongly. The trade's answer is cladding: a thin hard core wrapped in something softer and more stable, so only the exposed edge is vulnerable. Blenheim Forge describe soft iron cladding with a layer of nickel protecting the core, and a stainless-clad version of the same Aogami Super.

This is the detail that decides whether a knife suits your kitchen. A clad carbon knife needs wiping dry after use and will develop a grey patina that is cosmetic. A fully stainless knife needs nothing. Neither is a compromise; they are different agreements about who does the work.

• A hard core is clad in soft iron with a nickel layer protecting it. Blenheim Forge
• The same core is also offered clad in stainless. Blenheim Forge

Full tang, and the things that are not worth paying for

Full tang means the steel runs the whole length of the handle rather than stopping inside it, which is about balance and about the handle not parting from the blade in year eight. Robert Welch state it. It is worth having and it is also nearly universal above about forty pounds, so it is a thing to check rather than a thing to pay extra for.

What is not worth paying for: the number of layers in a damascus pattern, which is decoration and not strength; a knife block you did not choose; and a set. A set is how shops sell you four knives you will not use to get you the two you will.

• The blade runs the full length of the handle. Robert Welch

What a connoisseur actually does

Buy two knives, not six: one chef's knife or gyuto around 20cm, and one small paring knife. Match the hardness to your habits rather than your ambitions. Look for a named alloy and treat its absence as a missing specification. If you buy carbon, accept that you are now someone who dries a knife.

And learn to use a steel properly, which takes an afternoon. A 56 that is sharp cuts better than a 64 that is not, and the 64 spends more of its life blunt in most houses than the 56 does.

Kitchen knives we have judged for this

• Robert Welch Signature Cook's Knife, 20cm £68
• Sous Chef AUS10 Santoku, 16.5cm £109
• Senzo 33 Layer Gyuto, 240mm £199
• Kai Shun Wide Santoku, 18cm £183