Hocho Knife (Sushi Knife・Japanese chef knife) Official Blog

All about Aogami, highly ranked material for kitchen knives (1)

Introduction of Aogami, highly ranked material for Kitchen Knives

We are going to share with you about “Blue Paper Steel”, the highly ranked material for cutlery steel known as “Aoko” or “Aogami” in Japanese.

“Aogami” is an alloy steel made of Shirogami (or called “White Paper Steel”, a carbon steel with low content of impurities), mixed with tungsten and chromium, which means Aogami is a steel made by the hands of human. Among others, what matters the most is how sharp a knife edge can be and how long its sharpness can last. Plus, if it doesn’t take much to sharpen the edge, that’s fantastic. Some says that Aogami was used for an aim to achieve these features, while the material was originally developed for an edge of plane for shaving a wood pillar in Japan.

First, we’d like to touch on the definition of “Blue Paper” Steels, or “Aogami”.  There are three kinds of Aogami; “Ao-ichi ko (Aogami No.1) “, “Ao-ni ko (Aogami No.2)”, and “Aogami Super (Blue Paper Super)”. There are two types each for Aogami No.1 and No.2; Aogami No.1 A and B, and Aogami No.2 A and B, meaning 5 kinds of Aogami in total which are used for cutlery steel. steel. 

Second, we’d like to consider the differences between A and B of Aogami No.1 / No.2. ‘A’ is a steel material used for a hard edge knife so called “katakuchi hamono” in Japanese while ‘B’ for a less-hard edge knife called “amakuchi hamono” in Japanese.
The difference between A and B comes from the amount of carbon contained within. The more carbon, the harder a blade can be. Other than the amount of carbon, the remaining ingredients are all the same, meaning that the only difference between A and B is the amount of carbon. If a blade is hard, it can cut food well. At the same time, it needs to be paid attention because it is prone to form rust and chip off.  

The Blue Paper Steel has a high level of stickiness and abrasion resistance thanks to chromium and tungsten, so it can keep you from worrying about chipping-off and wearing-out of a blade to some extent compared to White Steel. Since the Blue Paper Steel contains a certain level of carbon, rusting and chipping are inevitable. We can’t tell the difference between A and B just by looking at them but we can by using and sharpening them. Also, the level of hardness varies depending on quenching and tempering temperature. Plus, depending on the skills of a blacksmith, A’s level of hardness can be as the same as B’s. 

It must be noted that “Aogami Super (Blue Paper Super)” is NOT necessarily the best in the 5 types of Aogami, sometimes the worst contrary to the hardness and price unfortunately.

We’ll explain the details about Aogami No.1 in the following chapters, that will be posted in series soon.
Keep your eyes on it!

Aogami No.1 (Blue Paper Steel No. 1)

Aogami No.2 (Blue Paper Steel No. 2)

Aogami Super (Blue Paper Super)

 

Check Aogami (Blue Paper Steel) Knives >

If you have any question, please feel free to contact us anytime.

Thank you for reading and best regards!

All the Hocho-Knife staff
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“Hocho” represents Made-in-Japan (Sushi / Sashimi) Kitchen Knives,
that is the soul of the cook!
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