Tetsujin Blue 2 Kasumi Nakiri 180mm

Part of the edge never reaches the board, so the cut never finishes. At our counter we put it simply: there is not enough flat at the heel. A knife with a long curve is built for rock chopping, not for the Chinese or Eastern up-and-down chop.

A straight edge, like a nakiri's, meets the board along its whole length and finishes the cut. On any knife, a dip worn near the heel or a dull section can cause the same thing.

The bevel. A Japanese dictionary describes the nakiri (菜切包丁) as shaped like an usuba but double-bevel and relatively easy to handle; the Sakai cutlery association describes the usuba (薄刃包丁) as an acute, wide knife for vegetables, in a square Kanto type and a kamagata Kansai type.

The names overlap, since another dictionary records the usuba as also called nakiri, so check the bevel rather than the name.

Yes, carbon steels such as Aogami (Blue) and Shirogami (White) are not stainless steels, so left wet they can spot or rust.

Care is simple once it becomes habit. Wipe the blade as you go, especially after acidic food like citrus, tomato or onion. When you finish, wash it in warm water with a little soap and dry it straight away with a towel. Do not let it air dry, leave it in the sink or the dish rack, or put it in the dishwasher. Store it dry: on a magnetic strip, in a saya or in a block in a dry spot.

If the knife will sit unused for a while, wipe on a thin layer of oil before storing. In our video James shows that mineral oil can stand in for camellia (tsubaki) oil, and he picks one labelled medical grade; we list the Kitchen Knife / Cutting Board Mineral Oil Medical Grade for this. If you find light rust, lift it with a rust eraser and a little water, then dry and oil the blade; we list the CKK and Naniwa rust erasers.

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.

A hamaguri-ba edge, written 蛤刃, is a convex edge shape, and it is the shape the workshop 明神利器製作所 sharpens its knives to. Kochi City's craft page records that the workshop's second generation, whose name the page gives as 直人, learned it over several years of training in Fukui.

The same page says the workshop also takes sharpening-only orders from outside Kochi.

Yes. Kochi City's craft page for his workshop 明神利器製作所 says the work runs from forging through finishing in one continuous process, 鍛造から仕上げまで一貫して行う.

That page lists the workshop in Susaki, Kochi.