Shibata Tinker Chibi Tank 180mm

It depends on the blade thickness. A knife maker's guide sorts the chuka cleaver (中華包丁) into three thicknesses, each suited to different foods.

The thin kind (薄刃), the lightest, is for the everyday foods a supermarket sells; the medium-thick kind (中厚刃) can also cut hard foods such as bone-in chicken and fish bones; and the thick kind (厚刃), the heaviest and meant for experienced users, suits bone-in block meat and frozen food. Check the thickness of your blade before you cut any bone.

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.

Aogami Blue steel, specifically Aogami Super (Blue Super), is a high-carbon Japanese knife steel made by Proterial that chefs value for its ability to take an extremely sharp edge and hold it longer than most other carbon steels, thanks to a composition with 1.40 to 1.50% carbon, 2.00 to 2.50% tungsten and 0.30 to 0.50% vanadium.

The "Blue" in Aogami refers to the color of the paper the steel is wrapped in at the mill, not the steel itself. Proterial describes Aogami Super as an alloy steel with tungsten, chromium and vanadium to improve heat-treatment properties and wear resistance. Proterial gives it a hardening hardness of over 60 HRC, giving you a blade that can be ground very thin for aggressive cutting performance while still resisting chipping in normal use. The trade-off is that, like all high-carbon steels, it is not stainless: it will rust if left wet or acidic, so you need to wipe it down and keep it dry.

Aogami (Blue) steel has less than half a percent of chromium, nowhere near what a stainless steel needs, so water left sitting on the blade will spot it. Dry it as soon as you finish, keep it somewhere dry, and let a patina build. Do that and aogami will hardly ever rust. On a stainless-clad knife only the thin line of aogami along the edge can rust; the cladding stays clean.

Will a carbon steel knife rust? covers patina, rust removal and which cladding rusts.

The difference is in Proterial's own figures: Aogami Super has 1.40 to 1.50% carbon, 2.00 to 2.50% tungsten, 0.30 to 0.50% chromium and 0.30 to 0.50% vanadium, against Aogami 2 (Blue 2) at 1.05 to 1.15% carbon, 1.00 to 1.50% tungsten and 0.20 to 0.50% chromium.

Proterial describes both as alloy steels with tungsten and chromium to improve heat-treatment properties and wear resistance, and also names vanadium for Aogami Super. Both pages list hardening hardness over 60 HRC, and Proterial lists Aogami Super for high-quality planes, other tipped tools, kitchen knives and sickles.

Tinker is a knife brand of cutler Takayuki Shibata, who owns and runs Shibata Knives. His site says his chef friends helped him develop it, combining playful design and functionality.

The site describes Tinker as outdoor-inspired knives suitable for any type of cooking, focusing on materials and shapes.

Shibata's site says a chef friend wanted a tough outdoor style knife that could do all kinds of cooking.

The site says that request led to TANK.

Yes, in part. Takayuki Shibata's own page for the Koutetsu line says of those knives, "we carefully sharpen them one by one."

From our own dealings with Iron Clad, he does the sharpening himself on knives that carry his name, though probably not on each one.

Iron Clad's company page lists resharpening among its business, with the export, maintenance and making of knives.