Hatsukokoro Aokitae Blue 2 Kurouchi Bunka 190mm Black Chacate

The bunka knife (文化包丁) takes its name from bunka, culture. A Sakai knife maker ties the name to Japan's modernisation, when Western culture and Japanese tradition merged, and says it stands for that new era and for the knife's wide range of uses.

The same maker says that as diets broadened to meat, fish and vegetables, an all-purpose knife was wanted, and the bunka took features from both Japanese and Western knives.

The tip. One Japanese knife maker describes the bunka (文化包丁, kengata) as combining the good points of the gyuto and the nakiri with the tip cut at an angle, and the santoku as coming after it, by rounding that tip.

Both are all-purpose knives for the home; santoku (三徳) means three virtues, for the three foods it cuts: meat, fish and vegetables.

Yes, carbon steels such as Aogami (Blue) and Shirogami (White) react with food, moisture, and acids, so left wet they can spot or rust. With normal use they develop a grey, blue and brown patina, and that patina is expected on a carbon knife rather than damage.

Aogami has only a little chromium, far below what a stainless steel needs, so water left sitting on the blade will spot it. A patina is a stable oxide layer that slows rust down; orange or red specks are rust.

Care is simple once it becomes habit:

• Wipe the blade as you go, especially after onion, citrus or tomato.
• When you finish, wash it in warm water with a little soap and dry it straight away with a towel. Don't let it air dry or leave it in the sink or the dish rack, and never put it in the dishwasher.
• Store it dry: on a magnetic strip, in a saya or in a block in a dry spot.
• If it's going to sit unused for a while, wipe on a thin film of food-safe mineral oil before storing it.

If you do find rust, lift light orange spots with a rust eraser and a little water, then dry and oil the blade. We stock the CKK and Naniwa rust erasers, and the Koyo Sunlite Polishing Paste (Blue for Steel) lifts light surface rust or refreshes a finish. Rust on the edge itself comes off the next time you sharpen. Deep pitting needs a professional sharpener. Avoid steel wool and harsh scouring on a polished or kurouchi finish, because they scratch it.

On a stainless-clad knife only the thin line of carbon steel along the edge can rust; the cladding stays clean. A carbon-clad or honyaki blade can rust over its whole face and needs the same care all over.

Carbon steel rewards this small amount of attention with a keener edge and easier sharpening than most stainless.

Proterial lists 1.05 to 1.15% carbon for both steels; its Blue 2 table lists 0.20 to 0.50% chromium and 1.00 to 1.50% tungsten, while its White 2 table lists neither.

Proterial describes White 2 as a carbon steel with minimum impurities and high hardness, and Blue 2 as an alloy steel with tungsten and chromium to improve heat-treatment properties and wear resistance, with a hardening hardness of over 60 HRC for both. Neither steel is close to the JSSA's 10.5% minimum for stainless.

We list it as a Blue 2 core clad in soft iron, with a kurouchi finish.

Proterial, the steelmaker, describes Aogami 2 (Blue 2) as an alloy steel with tungsten and chromium to improve heat treatment and wear resistance, and lists its hardening hardness as over 60 HRC.

Yes, it rusts if left wet. Proterial lists Blue 2 with 0.20% to 0.50% chromium, far under the Japan Stainless Steel Association's 10.5% line for stainless.

The soft iron cladding we list on this line is not stainless either, so dry the whole blade after use.

Hatsukokoro (初心) is a brand, not a forge. H&K, a company founded in 2013 and based in Amagasaki, Hyogo, created it in 2019.

H&K names the producer for some lines, for example Shinkiro by Takahiro Nihei in Fukushima, Ginyou by Yoshihiro Yauji in Echizen and Kurosagi by Motokyuichi Hamono in Nagasaki, and keeps others confidential. Some knives we stock carry the maker in the title, such as Hatsukokoro x Yoshikane SKD Nashiji.

The name comes from the Japanese proverb 初心忘るべからず, which means don't forget your original intention. The company read it gently as hatsukokoro rather than shoshin.

H&K created the brand in 2019, six years after the company was founded, and chose the name for its knife line.