How to care of and preserve carbon knives

How to care of and preserve carbon knives

There is a blog about knives that has been written for more than 15 years by Mr. Tatsuya Aoki, Suisin company owner, located in Sakai (Osaka Province), a city where 90% Japan’s professional knives are produced. The blog name is “SUISIN“, as well as the brand of his Knife System Co., Ltd company. This word means “overwhelming passion”.

Tatsuya Aoki describes his dedicated research with blades and his trajectory as a specialist in constant search for improvement. His blog is probably the most complete in Japan when it comes to detailed knife information. In fact, we at Miura Knives, have clarified many of our doubts in this blog.

From left to right: Tatsuya Aoki (Suisin owner) and Keiti Miura (Miura Knives owner)

Therefore, we will select and translate to English the most interesting and useful articles for you. We have the Mr. Aoki authorization, who will also collaborate by checking the texts or even rewriting in a simpler and understandable way even for non-professionals.

The first topic is “How to take care of the carbon knife and preserve it“.

Althougth the stainless steel knives are the most common, the carbon steel blade is the best when is about cutting. On this topic, we are going to explain the preservation technique to prevent the carbon steel knife rust.

During the use
While using the knife, some care needs to be taken. After cutting the food, wipe the knife with a damp cloth well-wrung. Otherwise, the blade may change color and rust. Vegetables like chives, that have liquid remnant, may cause blade color change even wiping it with cloth. On account of this, make the cleaning of the knife a habit during its use is really important.

After Use
After use, wash very well the knife with detergent, wipe with a dry cloth and store it in the box or in the sheath. If necessary, sharpen the blade. We will talk about sharpening when an opportunity comes up.

Although there are knife makers and books recommending the use of hot water and fire, Tatsuya Aoki does not recommended to use neither of both in order to dry the knife faster after washing, once the blade may crack due to thermal shock. And, also, passing the knife into the fire can cause the blade forge to return to its previous state, thus eliminating the hardness blade and thus the cutting line may end up soft and uncut.

In the case of the Mizu Honyaki Waboucho knife (Japanese knife forged entirely in a single steel and cooled in water), greater care must be taken! The real Japanese knife is extremely hard but, at the same time, delicate.

If is possible, pass a thin layer of oil on the knife and the finish will be perfect! It is recommended the use of specific oil for blades, but if you don’t have it, can be the olive oil that is available in any kitchen. If you pass the oil, wash the knife with detergent before using it.

In case of knife rusting

Even taking care, the knife can end up rusting. The carbon steel rust is not limited to the surface only, it spreads, eroding deeper, forming a kind of crater that makes impossible the blade sharpen. Because of this, is important to detect the rust during its starting, otherwise, it advances and becomes irreversible.

In the case of Japanese knives like yanagiba, deba and usuba, whose blade is single edged, the rust coming from the blade back (straight side) can deepen, reach the cutting line and damage it.

  1. Put a cleanser on a piece of greenery (turnip tip, cabbage middle, etc.) or paper towel.
  2. Put the knife on the cutting board and rub the rusted part.
  3. Blade cutting line: The correct position to avoid risk of injury is the handle turned to your side and the knife tip to the front. The movement is always from the beginning to the blade tip at the vertical.
  4. In the part where is the manufacturer’s name, the movements are diagonal, following the blade line.
  5. The back should also be wiped diagonally, following the lines.

There are special ‘erasers’ to remove rust (like the Sabitoru). The most indicated is the medium grammage.

If the rust can not be removed by using the wiper or eraser, a professional sharpener help is required.

Removing the stain
The greasy food might stain the carbon steel knife. It happens due to the reaction of the metal with the substances and it is not a serious problem like rust. It’s like a dirt on the blade. Although the stain does not damage the knife, its appearance is compromised, the food smell ends up in the knife and, also, the stain may cover a rust, so it is recommended to remove it using a cleaner. In this case, a special eraser for rust (Sabitoru) with finer grammage of finish is recommended.
















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