HAP-40 Petty Black 135mm (5.3″) – BLADE

HAP-40 Petty Black 135mm (5.3″) is a small kitchen knife from our HAP-40 series which we designed in collaboration with the Yoshida Hamono smithy. With this series, we fused Japanese tradition and knowledge of blade design and materials processing, and what came out is a versatile kitchen knife made of powder steel that is simple to use and maintain. To top it off, it boasts incredible properties, characteristic of only the best performing and most practical Japanese blades!

HAP-40 Petty Black embodies the best characteristics we could possibly expect from a kitchen knife: The shape of the blade allows for work on the cutting board, as well as for the in-hand use. The blade tapers off towards the tip and lends itself perfectly to precise work with food. Fine – and extremely long-lasting – sharpness. Very hard powder steel with a hardness of 68 HRC.  Simple maintenance and sharpening.

BLADE SHAPE:
Petty or utility knife is basically a smaller version of gyuto or chef’s knife, intended for all those smaller tasks where larger and wider knives are deemed unwieldy. A must-have in every kitchen, this small general-purpose knife is used for peeling and slicing fruit and vegetables, while its compact size and a relatively narrow blade also makes it very nimble and thus perfect for filleting fish, cutting poultry, slicing smaller pieces of dry meats and trimming meat. The blade is 135mm (5.3″) long.

HANDLE:
This knife is without a handle, so you can fit your own. Browse our selection of handles and create your own, custom-looking knife! If you would like that we fit the selected handle to the blade for you, select Handle fitting service when adding the blade to the cart.

STEEL:
The secret of this knife lies in extremely (68 HRC!) hard core made of a somewhat exotic and currently one of the most mysterious and attractive steels produced in Japan (at least as far as kitchen knives are concerned): Hitachi’s HAP-40 steel that fits into the category of modern and technologically advanced steels. HAP-40 is fine-grained enough to sharpen very well, and knives from this steel keep their sharpness 3-5 times longer than traditional knives. An interesting fact is that, considering it is a powder steel, it has an extremely small content of chromium (around 4%) and can react as a high-carbon steel in specific circumstances.

This steel is heat-treated to an incredible 68 HRC, yet it can still be relatively easily sharpened on whetstones. It is extremely tough, and so not as likely to chip along the edge as the steel used in traditional knives.

COMPOSITION: 1.27–1.37% carbon (C), 3.70–4.70% chromium (Cr), 5.60–6.40% tungsten (W), 4.60–5.40% molybdenum (Mo), 2.80–3.30% vanadium (V) and 7.50–8.50% cobalt (Co).

LAMINATION:
Osamu-san chose a warikomi (also called “split and insert”) method. A glowing hot piece of iron is split and a piece of steel is inserted. The new material is now forged into one piece composed of a very hard steel core in a jacket of two external layers of softer, stainless steel. This creates a highly durable kitchen knife with a slightly more pliable core. The main advantage of these knives is that they are thin, sharp and retain their edge very well.

GEOMETRY:
It has a double bevel (symmetrical) blade.

BLADE FINISH:
The blade has a dark finish which is the reason this look is also called kuro-uchi – the word “kuro” means black. This look is traditional and robust, with an unprocessed top part of the blade that has already developed a dark patina.

ABOUT THE BLACKSMITH:
The knife is manufactured at the smithy of Yoshida Hamono in Japan, a family company with an age-long tradition in manufacturing state-of-the-art tools and Japanese swords, i.e., katanas, by hand. Yoshida Hamono has a great deal of experience forging ZDP-189 steel in the traditional manner.