Japanese Knife Steels Explained: White, Blue, SLD, V2

White 1, Blue 2, SLD, V2, Swedish carbon… Every Japanese knife listing has a steel name, and most people have no idea what it means. Here I explain the steels used in the knives I sell: how they feel on the stone, how long they stay sharp and how much care they need. No chemistry lesson, only what matters when you cook and sharpen.

Short answer:
Want easy care → SLD semi-stainless (Tadafusa, Kaeru).
Want the sharpest edge and easiest sharpening → White 1 or White 2.
Want the edge to last longer → Blue 1 or Blue 2.
All carbon steels will rust if you leave them wet. Dry the knife and it is no problem.

Carbon, semi-stainless and stainless

Carbon steel is iron and carbon with very little else. It gets very hard, takes the finest edge and is a pleasure to sharpen, especially on natural stones. But it has no chromium, so it will rust and it gets a patina (dark colour) with use. Most knives on JNS are carbon steel.

Semi-stainless has around 11-13% chromium. Much harder to rust, still holds a very good edge. A little slower on the stone than carbon.

Stainless has even more chromium. Easy care, but most stainless steels don’t get as keen as carbon and don’t feel as nice on natural stones. I carry very few.

White and Blue steel (Yasugi steel)

White and Blue steel are made by Hitachi Metals (today called Proterial) in Yasugi, Shimane. That is why they are also called Yasugi steel. The names come from the colour of the paper label on the steel bars. Shirogami means white paper, Aogami means blue paper. The number tells you how much carbon: 1 has more carbon than 2, so it gets harder but is also a little more brittle.

White 2 (Shirogami 2 白紙2号)

The most common carbon steel in Japanese knives. Easy to sharpen, very forgiving.

Very pure carbon steel with almost nothing added. That purity is why it sharpens so fast and gets so sharp. It is a little softer and tougher than White 1, so it is more forgiving if you are not perfect with your technique. Loses its edge a bit faster than Blue, but comes back in a few minutes on the stone. Will rust, so dry it after use.

Carbon: approx. 1.0-1.2% · Hardness: approx. 61-64 HRC

At JNS: Wakui · Tanuki · Munetoshi

White 1 (Shirogami 1 白紙1号)

More carbon than White 2. Harder, sharper, needs more skill.

Same pure steel as White 2 but with more carbon. In the hands of a good smith it gets extremely hard and takes a crazy fine edge, and holds it longer than White 2. It is harder to forge and heat treat, so you mostly see it from top makers. A little more brittle, so don’t twist it in hard food or on bones.

Carbon: approx. 1.2-1.4% · Hardness: approx. 62-65 HRC

At JNS: Yoshikazu Tanaka · Yoshiaki Fujiwara · JNS Kokorozashi

Blue 2 (Aogami 2 青紙2号)

White steel with chromium and tungsten added. Holds the edge longer.

Blue steel starts from White steel and adds a little chromium and tungsten. That makes the edge last longer and the steel a bit tougher. The chromium is too little to make it stainless. It will still rust, only a little slower. On the stone it takes a bit longer than White, but it is still easy. A very good all-round steel for people who cook a lot.

Carbon: approx. 1.0-1.2% · Hardness: approx. 61-64 HRC

At JNS: Toyama · Tadafusa · Kaeru · Wakui

Blue 1 (Aogami 1 青紙1号)

More carbon than Blue 2. Very hard, very long edge life.

Blue 1 has more carbon than Blue 2, so it can be made harder and holds the edge even longer. It is a favourite of many top smiths. Takes a little more time on the stone, but the edge you get stays for a long time.

Carbon: approx. 1.2-1.4% · Hardness: approx. 62-65 HRC

At JNS: Yoshikazu Tanaka · Other knives

Aogami Super (Blue Super 青紙スーパー)

The hardest of the Yasugi carbon steels.

Even more carbon, chromium and tungsten than Blue 1, plus molybdenum and vanadium. Can be made very hard and holds an edge for a very long time. Slower to sharpen and less forgiving. Still carbon steel, so it can rust. I only get a few of these.

Carbon: approx. 1.4-1.5% · Hardness: approx. 63-65 HRC

Other carbon steels you will see on JNS

Swedish carbon (Shigefusa)

Shigefusa uses a Swedish carbon steel. The exact type is not published, so on my listings it says “Swedish Carbon, type unknown”. What you need to know: it is a clean carbon steel that takes a very fine edge. It will rust like any carbon steel.

At JNS: Shigefusa

V2 (Takefu carbon steel)

A simple carbon steel from Takefu Special Steel in Echizen. It behaves close to White 2. Easy to sharpen, gets very sharp, will rust. A good steel for a very fair price.

At JNS: Tanuki · Wakui · Kaeru

500 year old French anchor (bloomery iron)

A special project. The cladding is forged from bloomery iron from a 500 year old French anchor, with a 130WCrV5 steel core that is similar to Blue 1, water quenched. Old bloomery iron gives a wild, living pattern you can’t get from modern iron. Every knife is one of a kind.

At JNS: Toyama · Munetoshi

C145SC (JNS × Bryan Raquin)

A very clean, simple carbon steel from Germany (SC means “super clean”). Used in the JNS collaboration knives with French smith Bryan Raquin, usually with soft XC10 cladding.

At JNS: JNS Kokorozashi

Semi-stainless and stainless

SLD (semi-stainless)

The easy-care choice. Won’t rust unless you really ignore it.

A tool steel from Hitachi (Proterial) with around 12% chromium. Much harder to rust than carbon, and it holds an edge for a long time. It takes a little more time on the stone than White steel, but it sharpens fine on both synthetic and natural stones. The best choice for a first Japanese knife or a gift. SKD is a very similar steel.

Hardness: approx. 60-63 HRC

At JNS: Tadafusa · Kaeru

Ginsan, VG10 and ZDP-189 (stainless)

Ginsan (Silver 3) is a stainless steel that sharpens close to carbon steel. For me the nicest stainless on the stone. VG10 is the classic stainless in many Japanese knives, easy care but less fun to sharpen. ZDP-189 is a powder steel that gets extremely hard and holds an edge very long, but is slow to sharpen. I only get these now and then.

Clad knives and honyaki

Most Japanese knives are clad (also called san mai, warikomi or kasumi). A hard steel core makes the edge, and softer iron or stainless is forged on the outside. The soft outside makes the knife tougher and much easier to sharpen and thin.

Iron clad: the whole blade can rust and gets a patina. Shows a beautiful kasumi (misty) line when you polish it on natural stones.
Stainless clad: only the core at the edge can rust. Easier care, same edge.
Damascus clad: the outside is folded layers that make a pattern. It cuts the same as plain cladding, it is about looks.

Honyaki is made from one single piece of hard steel, no cladding. The smith quenches it with clay on the spine, often in water, which gives the hamon (temper line). It is very difficult and many blades crack in the quench, so honyaki is rare and expensive. It is very stiff, holds a great edge, but it takes more time to sharpen and thin, and the whole blade is hard, so it must be handled with care.

Water quenched (you see this on some listings) means the blade was cooled in water instead of oil. Water is faster and can give a harder edge, but it is much riskier for the smith. Only very skilled smiths do it.

Quick comparison

Steel	Type	Rust risk	Sharpening	Edge holding	Hardness
White 2	Carbon	High	Very easy	Good	61-64
White 1	Carbon	High	Very easy	Very good	62-65
V2	Carbon	High	Very easy	Good	61-64
Swedish carbon	Carbon	High	Very easy	Very good	varies
Blue 2	Carbon	Medium-high	Easy	Very good	61-64
Blue 1	Carbon	Medium-high	Easy	Excellent	62-65
Aogami Super	Carbon	Medium	Slower	Excellent	63-65
SLD	Semi-stainless	Low	Easy	Very good	60-63
Ginsan	Stainless	Very low	Easy	Good	60-62

Hardness in HRC, approximate. The real number depends on the smith and the heat treatment. A great smith with White 2 will beat an average smith with Aogami Super.

Living with carbon steel

Wipe the knife dry after use. That is the one rule.
Don’t leave it wet in the sink and never put it in the dishwasher.
It will get a grey or blue patina. That is normal and it protects the steel a little.
If you don’t use it for a long time, put a thin layer of camellia oil on the blade.
Small orange rust spots come off easily with a cork and some fine abrasive. Don’t wait with it.

Which knife shape → Japanese Knife Types
Your first Japanese knife → First Japanese Kitchen Knife
Stones for your knife → Stones Recommendations
Get the kasumi finish on clad knives → Kasumi on Hard Jnats

Questions about a specific knife? Send me a message on WhatsApp or email.

HELP

Japanese Knife Steels