Couteaux en carbone 101

Carbon Knives 101

Do you have a carbon knife or do you think you have one?
This article is for you!


  • A patina (grey-black) will form naturally, that's a good thing! Once the knife has a patina, it becomes protected against rust. 
  • The first uses of a carbon knife are critical. It is absolutely necessary to wipe the knife immediately after use, a single oversight does not forgive since the blade is not yet well protected by the patina.
  • If we see rust spots, it does not matter, we have the rust eraser for Japanese knives.
  • A carbon blade sharpens much easier and has the ability to be sharper.

In detail: 

There are two main categories of metals for making knives; 

  • stainless steel
    • (VG10 / SG2 / Ginsan / etc.)
  • Carbon 
    • (Shirogami / Aogami / Aogami Super)

The stainless steel knives hardly rust, but generally less easy to sharpen and less sharp than carbon. Have no fear, Japanese stainless steel knives are still sharper than the majority of knives in the world. The big advantage of stainless steel knives is that they hardly rust.

The carbon knives are extremely sharp, very easy to sharpen, but can oxidize. For many, the oxidation is rather beautiful and adds a story to the knife. This natural oxidation is called patina. 

The first uses of the carbon knife are critical in order to avoid unwanted oxidation; rust. After several uses, a natural protection (patina) forms and there is much less danger of our new knife rusting. 

Among our knives, we find the collections Tanaka AoTanaka Shiro and Kintaro AS having steels high grade carbon (Shirogami, Aogami or Aogami Super). Shirogami and Aogami steels have been traditional steels for making knives long before stainless steel existed. It has a mystical and historical side all its own. In Japan, it was the traditional material for making samurai swords.

Preparing food with a high carbon steel knife connects the user to a millennia-old story.

The patina is an alteration in the appearance of objects and materials, such as steel, under the effect of time. The knife will protect itself against reddish oxidation, see rust. If your knife changes to grayish or black, that's what we want.


If, on the other hand, it turns red, you will need a rust eraser to remove the stains without damaging the blade.

Like all high carbon steel, it is very important to wipe the blade immediately after use. It is also advisable to maintain it with Camellia oil from Couteaux Nagano if you plan to store your knife for a long period of time.

If, despite all precautions, a reddish color forms, simply use our rust eraser. You can also gently rub the blade with baking soda. Go slowly so you don't remove all the patina you've already developed.


When you use your knives on foods like onions, tomatoes, lemons, or other acidic foods, you'll notice the patina getting darker. Carbon knives that have a strong patina will be recognized as a reward for using exceptional knives. Your knife will be unique to you and no other can look like it. It's your knife!

Some knives, like those in our collections "Miki Tsuchime", "Miki Kenma" and "Hana Series", have a high carbon steel core, but with a stainless steel coating. These knives require a little less maintenance, as the carbon steel is only found on the edge of the blade.

Here is a very easy tip for high carbon steel knives; you keep one dry cloth nearby when cooking. It will therefore be easy to wipe your knife in order to avoid the worst. Do not put the knife back in its original paper, it would retain moisture and oxidize.

A knife magnet is also recommended in order to allow the knife to dry properly without remaining locked in humidity. 

We 100% recommend high carbon knives, but be warned, your knife will "come to life" the first time you use it. If you don't want an "upgradable" knife, we have some great options in Japanese stainless steel!

Bruno's favorite collection: Tanaka Shiro by its authenticity, its look, its price and its incredible sharpness.  


Back to blog

Leave a comment

Please note, comments need to be approved before they are published.