Knife Steel Information

There are many different types of knife steels available, each with its own set of unique metallurgy, traits and characteristics.

The two main umbrella terms used to describe the different kinds of steel are Stainless Steel and Carbon Steel.

Stainless steel is used to describe steel that has at least 10.5% chromium content by mass. It gains its 'stainless' properties primarily due to the presence of chromium (Cr), which is a key alloying element. This chromium content forms a passive oxide layer on the surface of the steel, which prevents corrosion and makes it "stainless", or resistant to rust and staining.

Japanese handmade kitchen knives often use specific stainless steels known for their performance, edge retention, and ease of maintenance.

While the steel itself is important, so is the treatment of this steel. As such, different blacksmiths and steel companies have their own processes and heat treatments, making each knife unique to the individual (or individuals) who made it.

We recommend choosing a knife based on your own personal preference.

The two biggest decisions one needs to make (at least in our opinion), is:

1- How much maintenance are you willing to put in?

2- Do you want stainless or carbon?

Buy something that you will use, and that will bring you happiness and the most enjoyment out of cooking. That is what Japanese knives are made for.

This is a simple guide, but if you are really into your steel, then we highly recommend checking out the wealth of information available, (from people much smarter than us!), on Knife Steel Nerds. We have no affiliation. We only suggest them as their website is a solid, well known source for a more in depth deep dive down the rabbit hole of knife steels.

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Quick Steel Comparison Table

 

Understanding HRC - Rockwell Hardness

HRC stands for Hardness Rockwell C scale — the standard measure of steel hardness used in knife-making. The higher the number, the harder the steel.

What does hardness mean for you?

• Higher HRC (64+): Holds a sharper edge longer, but more brittle — can chip if used on hard foods or bones.
• Lower HRC (58-61): More flexible and forgiving, easier to sharpen, but requires more frequent honing.
• Japanese knives typically range from 60-67 HRC — significantly harder than most Western knives (54-58 HRC), which is why they hold such fine edges.

A knife at 65 HRC is not "better" than one at 61 HRC — it depends entirely on how you cook and how much maintenance you want to do.

 

Damascus & Clad Steel - What Does It Mean?

Many of our knives are described as Damascus or Warikomi (clad). These terms refer to the construction method, not the core steel itself.

Clad / Warikomi: A hard, high-performance steel core (e.g. Aogami Super, VG-10) is sandwiched between layers of softer stainless or iron cladding. The cladding protects the core, adds toughness, and reduces the maintenance burden — only the exposed edge is carbon steel. This is the construction used on many of our Shinobi Industries branded knives.

Damascus: Multiple layers of steel are folded and forge-welded together, creating the distinctive flowing, wavy pattern on the blade. Damascus can be purely aesthetic (a pattern-welded jacket over a mono-steel core) or structural. Either way, the cutting performance is determined by the core steel — the Damascus layers add beauty and character.

When you see "Stainless clad Aogami Super" on one of our knives, it means you get the elite edge retention of Aogami Super with the easier maintenance of a stainless exterior.

 

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Here are some of the main types of Carbon steel commonly used for making Japanese cutlery and kitchen knives:

 

Shirogami (白鋼)

Also known as White Steel, or white paper steel, is a type of high-carbon steel used primarily in the production of traditional Japanese kitchen knives.

Composition:
Shirogami #1 / White Steel #1 (白一鋼):
- Carbon (C): Approximately 1.25-1.35%
- Manganese (Mn): Approximately 0.10-0.30%
- Silicon (Si): Approximately 0.10-0.30%
- Phosphorus (P) and Sulfur (S): Minimal amounts
- Iron (Fe): Balance

Shirogami #2 / White Steel #2 (白ニ鋼):
- Carbon (C): Approximately 1.00-1.10%
- Manganese (Mn): Approximately 0.10-0.30%
- Silicon (Si): Approximately 0.10-0.30%
- Phosphorus (P) and Sulfur (S): Minimal amounts
- Iron (Fe): Balance

Hardness: Shirogami is hardened to between 60 and 65 HRC — high enough to take an exceptionally fine edge, but demanding of proper technique and care.

Sharpness: Few steels match Shirogami for pure, refined sharpness. Its simple, ultra-pure composition allows it to be ground to a very acute edge angle, making it a favourite among traditional Japanese craftsmen and chefs alike.

Edge Retention: Shirogami sharpens easily and responds beautifully to a whetstone, but it is more delicate than Aogami. It is best suited to cooks who prioritise absolute sharpness over long-term edge durability.

Corrosion Resistance: As a high-carbon steel with minimal alloying elements, Shirogami is reactive. It will patina quickly — especially with acidic ingredients — and will rust if left wet or neglected. Dry the blade immediately after use, oil it periodically, and the patina that develops will actually help protect it over time.

Maker: Hitachi Metals Ltd. (Yasugi Specialty Steel), located in Yasugi City, Shimane Prefecture, Japan.

 

Aogami (青紙)

Also known as Blue Steel, or Blue Paper Steel, is a group of high-carbon steels commonly used in the production of Japanese kitchen knives.

Composition:
Aogami #1 / Blue Steel #1 (青一鋼):
- Carbon (C): Approximately 1.10-1.30%
- Silicon (Si): Approximately 0.10-0.50%
- Manganese (Mn): Approximately 0.10-0.50%
- Tungsten (W): Approximately 1.50-2.00%
- Chromium (Cr): Approximately 0.20-0.50%
- Vanadium (V): Approximately 0.10-0.30%

Aogami #2 / Blue Steel #2 (青ニ鋼):
- Carbon (C): Approximately 0.95-1.05%
- Silicon (Si): Approximately 0.10-0.50%
- Manganese (Mn): Approximately 0.10-0.50%
- Tungsten (W): Approximately 1.00-1.50%
- Chromium (Cr): Approximately 0.20-0.50%
- Vanadium (V): Approximately 0.10-0.30%

Hardness: Aogami is typically hardened to 62-64 HRC after heat treatment — harder than most Western knives, and hard enough to hold a refined edge through serious kitchen use.

Edge Retention: The addition of tungsten and vanadium gives Aogami meaningfully better edge retention than Shirogami, making it a strong choice for cooks who want a high-performance carbon steel they don't need to touch up constantly.

Corrosion Resistance: Aogami is slightly more forgiving than Shirogami thanks to its additional alloying elements, but it is still a carbon steel — it will patina with use and rust if left wet. Treat it with the same care and respect you'd give any fine carbon blade.

Maker: Aogami steel is produced by several Japanese steel manufacturers, with Hitachi Metals Ltd. being one of the primary producers.

 

Aogami Super (青紙スーパー)

Also known as Aogami Super Blue or AS steel, it is a premium high-carbon steel highly regarded in the world of Japanese kitchen knives.

Composition:
- Carbon (C): Approximately 1.40-1.50%
- Silicon (Si): Approximately 0.10-0.50%
- Manganese (Mn): Approximately 0.10-0.50%
- Tungsten (W): Approximately 2.00-2.50%
- Chromium (Cr): Approximately 0.30-0.50%
- Vanadium (V): Approximately 0.10-0.30%
- Molybdenum (Mo): Approximately 0.30-0.50%

Hardness: Aogami Super is typically hardened to around 64-65 HRC — placing it among the hardest steels used in kitchen knife production. At this level, edge retention is exceptional, but the steel demands respect: use it on appropriate cutting surfaces and avoid lateral stress on the blade.

Edge Retention: This is where Aogami Super earns its reputation. The elevated carbon content combined with tungsten, vanadium, and molybdenum produces a steel that holds its edge under demanding, sustained use. For cooks who sharpen infrequently but expect consistent performance, it is hard to beat.

Corrosion Resistance: Like all high-carbon steels, Aogami Super is not stainless. It will develop a patina with regular use — which is normal and desirable — but it must be dried immediately after use and oiled periodically to prevent rust.

Maker: Aogami Super steel is produced by Hitachi Metals Ltd.

Aogami Super represents the pinnacle of high-carbon steel craftsmanship in Japanese knife-making — a steel that rewards those who understand it with extraordinary cutting performance.

 

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Here are some of the main types of stainless steel commonly used for making Japanese cutlery and kitchen knives:

 

VG-10
Composition:
- Carbon: Approximately 1.00%
- Chromium: Approximately 15%
- Molybdenum: Approximately 1.00%
- Vanadium: Approximately 0.20%

Characteristics: VG-10 is one of the most widely used stainless steels in Japanese knife-making, and for good reason. It strikes a reliable balance between edge retention, corrosion resistance, and ease of sharpening — making it an excellent choice for cooks who want genuine performance without the maintenance demands of carbon steel. It holds up well in busy kitchen environments and responds readily to a whetstone when the time comes.

 

R2/SG2
Composition: R2 (also known as SG2) is a powdered metallurgy stainless steel with a composition that generally includes:
- Carbon: Approximately 1.25%
- Chromium: Approximately 14%
- Molybdenum: Approximately 2.30%
- Vanadium: Approximately 0.30%

Characteristics: Produced using a powdered metallurgy process, R2/SG2 achieves a level of microstructural consistency that conventional steels cannot match. The result is a stainless steel with exceptional hardness, outstanding edge retention, and good toughness — qualities that make it a popular choice for high-end Japanese kitchen knives. It offers much of the performance of a premium carbon steel with the corrosion resistance of stainless.

 

Ginsan / Ginsanko / Silver 3 (銀三)

Ginsan, also known as Ginsanko or Silver 3, is a stainless steel alloy used primarily in the production of high-quality Japanese kitchen knives.

Maker: Ginsan steel is manufactured by Hitachi Metals Ltd.

Composition:
- Carbon (C): Approximately 0.95%
- Chromium (Cr): Approximately 13-15%
- Nickel (Ni): Approximately 0.60-1.00%
- Manganese (Mn), Silicon (Si), and other trace elements in smaller quantities.

Characteristics: Ginsan occupies a unique position in the Japanese knife steel landscape. Its high chromium content delivers genuine stainless performance — resistant to rust and easy to maintain — while its carbon content and relatively simple alloy structure give it a sharpening feel and edge quality that is closer to carbon steel than most stainless options. For cooks who want the refinement of a carbon-style edge without the corrosion anxiety, Ginsan is a compelling choice.

 

HAP40 (semi-stainless)

HAP40 is a powdered high-speed tool steel that is sometimes used in Japanese kitchen knives.

Maker: Hitachi Metals, Ltd. (now known as Proterial), Japan.

Composition:
- Carbon: Approximately 1.30%
- Chromium: Approximately 4.00%
- Molybdenum: Approximately 5.00%
- Vanadium: Approximately 5.00%

Characteristics: HAP40 was originally developed as an industrial tool steel, and its performance in kitchen knives reflects that heritage. Hardened to 66-68 HRC, it sits at the very top of the hardness range for kitchen use — delivering extraordinary edge retention that outlasts most other steels. It is not a steel for the casual cook; it requires proper maintenance and appropriate cutting surfaces. But in the right hands, it makes an exceptional blade.

 

ZA-18

ZA-18 is a stainless steel developed through a partnership between Aichi Steel Corp and Osaka Clad Co., Ltd. It is known for its specific composition and properties suited for various industrial and knife-making applications.

Maker: Developed through a partnership between Aichi Steel Corp and Osaka Clad Co., Ltd.

Composition
- Carbon (C): Approximately 0.95-1.2%
- Chromium (Cr): Approximately 17-19%
- Nickel (Ni): Approximately 8-10%
- Molybdenum (Mo): Approximately 1.5%
- Copper (Cu): Approximately 1.00%
- Cobalt (Co): Approximately 1.8%
- Other trace elements: Silicon (Si), manganese (Mn), sulfur (S), phosphorus (P)

• Corrosion Resistance: ZA-18's high chromium and nickel content gives it some of the best corrosion resistance of any steel used in Japanese kitchen knives — well suited to demanding, high-moisture environments.
• Strength and Toughness: The balanced alloy composition produces a steel that is both hard and tough, resisting chipping under normal kitchen use.
• Machinability: ZA-18 responds well to the forging and grinding processes used by Japanese knife makers, allowing for precise geometry and refined finishes.
• Heat Resistance: The chromium and nickel content also contributes to good heat resistance, maintaining structural integrity under the thermal stresses of professional kitchen use.

These stainless steels are chosen for their specific properties that cater to different preferences and needs among chefs and knife enthusiasts.

 

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Choosing Steel by Skill Level

Beginner / Home Cook: Start with stainless. VG-10 or Ginsan (Silver 3) give you excellent performance without the rust anxiety. Easy to maintain, forgiving to sharpen.

Intermediate / Enthusiast: Consider Aogami #2 or Ginsan. You'll appreciate the edge quality, and you're ready to learn proper drying and occasional oiling habits.

Advanced / Professional: Aogami Super, HAP40, or R2/SG2. These steels reward proper technique and care with extraordinary cutting performance. Not for the faint-hearted — or the dishwasher.

 

Care & Maintenance by Steel Type

Carbon Steel (Shirogami, Aogami, Aogami Super):

• Wipe and dry immediately after use — never leave wet.
• Apply a thin coat of food-safe oil (camellia oil is traditional) after drying.
• Expect and embrace a patina — it's natural and actually helps protect the blade.
• Avoid acidic foods sitting on the blade for extended periods.
• Never put in the dishwasher.

Stainless Steel (VG-10, Ginsan, R2/SG2, ZA-18):

• Rinse and dry after use — stainless is resistant to rust, not immune.
• No oiling required, but occasional oiling won't hurt.
• Still hand-wash only — dishwashers damage handles and edges.

Clad / Warikomi knives: Follow carbon steel care for the edge, stainless care for the cladding. When in doubt, treat it as carbon.

 

Frequently Asked Questions

Is VG-10 better than Aogami?
Neither is objectively better — they serve different needs. VG-10 is stainless and low-maintenance. Aogami is carbon steel that takes a finer, sharper edge but requires more care. If you want ease, choose VG-10. If you want the sharpest possible edge and enjoy the ritual of knife care, choose Aogami.

What steel do professional chefs use?
It varies widely. Many Japanese professionals use Aogami Super or Shirogami for its sharpness. Western-trained chefs often prefer VG-10 or R2/SG2 for their balance of performance and durability. The best steel is the one that suits your cooking style and maintenance habits.

How do I stop my carbon steel knife from rusting?
Dry it immediately after use, apply a thin coat of camellia or mineral oil, and store it in a dry place. A patina (dark discolouration) is not rust — it's a protective layer. Actual rust (orange/red spots) can be removed with a rust eraser or fine wet-and-dry sandpaper.

What is the difference between Aogami #1 and Aogami #2?
Aogami #1 has slightly higher carbon content, making it harder and offering better edge retention. Aogami #2 is slightly tougher and easier to sharpen. Both are excellent — #2 is more common and considered the more versatile of the two.

Can I put my Japanese knife in the dishwasher?
No. The heat, moisture, and detergents will damage the handle, dull the edge, and can cause rust even on stainless steel knives. Always hand-wash and dry immediately.

 

Where are these steels produced?

There are several Japanese companies renowned for their expertise in producing high-quality knife steels:

Hitachi Metals Ltd.
One of the most well-known manufacturers of speciality steels in Japan, including carbon steels (Shirogami, Aogami) and stainless steels (VG-10, Ginsan). Now operating under the name Proterial.

Aichi Steel Corporation
Another major Japanese steel manufacturer known for producing specialty steels. Co-developed ZA-18 in partnership with Osaka Clad Co., Ltd.

Osaka Clad Co., Ltd.
Co-developed ZA-18 in partnership with Aichi Steel Corp, known for producing clad and specialty steels for knife-making applications.

Takefu Special Steel Co., Ltd.
Specialises in producing high-performance tool steels and stainless steels that are highly favoured by Japanese knife makers.

Yasugi Specialty Steel
Part of Hitachi Metals Ltd., located in Yasugi City, Shimane Prefecture, Japan. Known for producing traditional Japanese carbon steels used in knives, such as Shirogami and Aogami series.

Niigata Seiki Co., Ltd.
Specialises in manufacturing high-quality stainless steels used in the production of kitchen knives and other cutlery items.

These companies play a crucial role in the Japanese knife-making industry, supplying knife makers and manufacturers with the high-quality steels needed to create knives renowned for their sharpness, edge retention, and durability.

 

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While there are other international companies and knife retailers who claim to use Japanese steel, Shinobi Industries takes pride in the fact that all of our knives are made in Japan by Japanese craftsmen using only the highest quality Japanese steel.