Why I changed my knife buying habits – carbon steel knives

As a keen cook and a lover of quality tools I have always enjoyed using quality kitchen knives and pride myself on keeping them sharpened and honed to maintain the keenest of edges. It is said that a blunt knife is a dangerous knife whilst a sharp knife is easy to operate and treated with care and respect will be a joy to use.

Recently, though, I made a discovery that has changed my knife buying for good. I discovered the wonders of carbon steel knives. Stainless Steel is the usual choice for kitchen knives and for a good reason , they don’t rust. So why do professional chefs use carbon steel knives?opinel2web

In this photo you see two virtually identical Opinel paring knives. The one with the yellow handle has a stainless steel blade (note the word “inox” on the blade) where the knife with the natural wood coloured handle has a blade of carbon steel (and has “Carbone” indicating this on the blade). The stainless steel version looks nice and shiny – so that is obviously the ‘best’ knife right? Well, it is not my favourite… I prefer the carbon steel version but carbon steel knives are not for everyone. Let me explain.

Stainless steel knives are very low maintenance. They can be left wet and will not rust, well that is not strictly true, but the chromium in the stainless steel reacts with oxygen in the air to form a very thin layer of chromium oxide (Cr2O3) which then forms a protective layer to prevent rust. In contrast carbon steel knives will rust quickly if left wet for even the briefest of periods. So if you choose carbon steel then you will have to be fairly regimented when it comes to looking after your knives, they should be cleaned and dried thoroughly after each and every use to prevent rust.

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You will notice that the stainless blade above (the uppermost one in the photo) is shiny and beautiful looking where the carbon steel blade is a deep mottled grey, blue colour which is as far from shiny as one could imagine. Whilst this might appear unsightly to those who love shiny things (my wife for one) to others, including myself, this mottled patina to the blade is super desirable.

This mottled patination is desirable firstly because it offers some protection against rust. It is actually a form of oxidation in itself, but helps to prevent deeper and harmful rust spots that can eat in to the blade causing pitting. So what is the difference? Well, when iron in the steel oxidises in the presence of water is forms hydrated Iron Oxide, which is the type of red rust that we all know and try to avoid. When this blue / black patina is formed stable Iron Oxide is formed and acts as a protective coating on the steel, although it is easily scratched and will wear off so is not a permanent protection against further corrosion so care must still be taken to look after your knife. This blue / black patina can be ‘forced’ by exposing the blade to certain acids found in many foods such as lemon juice, tomato ketchup & onions to name just a few.

I personally love the aesthetics of the patina. It’s uneven mottled appearance is ever changing on the blade and as it develops it tells a story of it’s history. This appeals to me as each and every blade will develop it’s own unique patina and character. Like an old leather Chesterfield or a well used butchers block where years of use translates directly in to the most beautiful, comfortable and weathered appearance and makes the item more appealing.

So, if carbon steel knives are much higher maintenance then why would anyone choose one over a stainless version? Carbon steel knives do have some advantages other than being beautiful. The high carbon content improves strength and hardness and because of this they keep an edge sharp for longer and that is a great thing when it comes to knives, right? That is the whole point of a knife so if you strive for the sharpest knife then you much choose a carbon steel knife.

Carbon steel knives may not be for everyone, but for those who value sharpness over ease of maintenance and those who appreciate the beauty and ever changing patination of the blade more than they appreciate a sterile looking shiny stainless blade then there is only one choice for your knives, and that choice is carbon steel.