Knives made of Carbon Steel

Advice & Tips

Rene Djuricek 03/03/2024 0 Comments

When you look for Japanese knives, you quickly come across steels such as Aogami and Shirogami. These are steels with high carbon (carbon) content that have advantages and disadvantages. So read this article first to see if these steels are the right choice for you.

What is carbon steel / carbon steel?

Steel consists of a combination of iron and carbon where carbon makes the steel hard. So the more carbon, the harder the steel. But at the same time, carbon also makes steel more susceptible to rust and patina.

To combat this, Chromium is often added. To call a steel stainless, it must contain at least 11% Chromium. But adding Chromium makes a knife harder to sharpen. You'll notice this in the sharpness out of the box and in self-trimming.

So carbon steel is steel with a high carbon content and less than 11% Chromium.

Why carbon instead of stainless steel

Carbon knives stay sharp longer and are much easier to resharpen yourself. This is because carbon steel is more pure (fewer additional components) which makes it more responsive. Another reason is that carbon knives feel different while cutting. They feel even sharper and make cutting even more fun. Once you get used it to carbon steel, you will never want anything else.

Patina layer

Carbon knives are prone to rust, which is why they require a little more maintenance than stainless steel knives. Fortunately, the steel receives natural protection in the form of a patina layer.

A patina layer is a thin layer of oxidation over the steel. This layer is formed by salt, acid and/or moisture. Thus, when cutting ingredients with high acidity, the layer will form faster, but also, for example, the sweat in your finger can discolor the knife steel.

It is good to know that especially in the beginning, patina forms quickly. Once the knife has a patina layer it will not discolor quickly.

You can recognize a patina layer by a yellow or blue color that appears on the knife. The color depends on the steel used and what you cut. With each knife, the pattern and color is different. Also, over time, the color can change to a grayish color. Many chefs proudly show how the patina is formed on the knife. It is a sign of good care and a chef's passion.

Patina protects the steel from further oxidation, that is, in part from rust. Still, you should clean and dry the steel well after use to keep it in the best condition. If the steel is in contact with acids or water for too long then rust will still occur.

This is also why your Japanese chefs always have two cloths next to their cutting boards.

You can also force the formation of patina with coffee, vinegar or mustard.

Sanmai (multiple layers) steel

A technique that has been widely used in recent years is the Sanmai technique. This involves folding layers of stainless steel over the carbon core steel. These layers protect the steel from rust and make it less susceptible to breakage.

With stainless Sanmai, you have the benefits of carbon steel with almost the same ease as a stainless knife. These are also our favorite kind of knives. Fun fact is that Fujiwara San designed this technique.

The outer layers can also be made of carbon. In that case, this is done to make the core steel more flexible. The outer layers will themselves develop a patina layer and can rust with improper maintenance.

Maintaining carbon steel

Maintaining a carbon knife does not have to be complicated. Just make sure you wash the knife well after use and dry it carefully. It normally doesn't need much more than that.

Do you cut acidic ingredients such as tomatoes, onions or fruit? Then also rinse your knife in between ingredients. This will prevent the acids from damaging the patina layer.

It is best to have a damp cloth or kitchen paper next to your cutting board with which to wipe the knife each time.

This is how to maintain a carbon steel knife:

Properly washing a carbon steel knife
Use warm water with a little soap and a sponge
Polish the knife (no need to scrub)
Rinse the knife
Dry the knife well with a dry cloth
Periodically put a drop of(camellia) oil on the blade and spread it well.

Help my knife rust!

No problem! This is a property of the steel and is usually easy to solve.

For a quick fix, you need a lime. Cut the lime in half and squeeze a few drops onto the rust stain. Let this take effect for a few seconds and then smear the rust spot with the peel of the lime. You will see that this will make the spot disappear.

Is the rust already more stubborn? Then use a rust eraser. This is a small sanding block that you use to sand away the rust. Note that this will leave tiny scratches on the knife.

After this, lubricate the knife with neutral oil. The best way to do this is to use camellia oil. This oil has been used for centuries to protect knives and samurai swords from rust.

White paper and Blue paper

A fun fact is that the name of these steels have nothing to do with the color of the steel. They got this name because they come with a blue or white label.

Most Popular Carbon Knives

Are you convinced you want a knife made of carbon steel? Then read the Most Popular Carbon Knives article to see the best-selling models. All with helpful information to make the choice a little easier.