Japanese plane steels: how to choose the right Kanna blade

Choosing the steel is an essential element when selecting a Japanese plane: a Kanna. Depending on the species of wood being worked, the desired hardness, ease of sharpening, or edge retention, one steel may be more suitable than another.

Japanese planes, some of which are manufactured in Miki, Japan, are offered in different types of steel: from traditional White Steel (Shirogami) to alloy steels like Blue Steel (Aogami), and even high-speed HSS steels intended for the most demanding work.

Understanding the main families of steel therefore makes it possible to choose a Kanna based on its intended use rather than simply searching for "the best steel."

The traditional construction of a Kanna blade

The blade of a traditional Japanese plane is generally made of two different steels.

The soft backing steel, called Jigane. Laminated to the cutting steel, it allows the blade to be resilient, and above all, to use a minimum amount of cutting steel during the forging process. This laminated construction offers several advantages: it allows for a very hard edge and a thick blade, which facilitates sharpening, especially when done freehand.

A thin layer of very hard steel, called Hagane, forms the cutting edge.

This is one of the features that characterize the blades of traditional Japanese tools.

The main families of steels used for Kanna

The steels used in Tsunesaburo Japanese planes can be simplified into three main families:

• carbon steels, notably White Steel;

• alloy steels, such as Blue Steel, Super Blue, or certain Swedish steels;

• high-speed HSS steels, such as SKH51 or HAP40.

Each family prioritizes a different balance between fineness of the edge, ease of sharpening, wear resistance, and edge retention.

White Steel: the choice for a fine edge

White Steel, or Shirogami, is a carbon steel particularly prized in Japanese tools.

Its composition, relatively free of alloying elements, facilitates sharpening and allows for an extremely fine edge.

It is a particularly interesting steel for softwoods and species that require a very fine edge, such as cedar or paulownia.

Its main advantages

• excellent sharpening potential;

• fast and pleasant sharpening;

very fine cutting sensation;

• particularly suitable for softwoods.

In return, its wear resistance is generally lower than that of a highly alloyed steel.

For a craftsman who prioritizes the fineness of the edge and the pleasure of sharpening, White Steel remains an essential reference.

Blue Steel: greater edge retention

Blue Steel, or Aogami, is a carbon steel to which various alloying elements have been added, notably tungsten and chromium.

These additions improve wear resistance and edge retention.

The result is a steel that is particularly interesting for working hardwoods, when you want to maintain an effective edge for longer.

The compromise is slightly different from White Steel: sharpening generally requires a little more time, but the blade can perform well for longer between sharpenings.

Blue Steel #1

Blue Steel #1 is traditionally prized for high-end Japanese plane blades.

It offers a good balance between:

• hardness;

• wear resistance;

• toughness;

• edge quality;

• ease of use.

Some Tsunesaburo blades also use variants or specially forged steels, whose characteristics may differ from standard grades.

Super Blue Steel: a high-end alloy steel

Super Blue Steel is a more heavily alloyed evolution of Blue steels.

Its composition combines carbon, tungsten, and molybdenum, among others, to obtain an excellent compromise between hardness, edge retention, and cutting quality.

It can be suitable for a wide variety of species and is an interesting choice for users who are looking for a versatile blade with good wear resistance.

Swedish steels: fineness and ease of use

Some Tsunesaburo planes have also been offered with Swedish steels, notably from Sandvik or Assab production.

These steels are appreciated for their high purity and their ability to produce a fine edge while maintaining good durability.

They are, in particular, an interesting option for medium-hardness woods.

Special steels: for more targeted uses

Tsunesaburo has also used different, more specific grades of steel.

Forged Blue #1

This steel, specifically commissioned and historically worked for Tsunesaburo, is characterized by its ease of sharpening and a particularly fine edge.

It can be particularly interesting for softwoods.

Special Blade Steel

This tungsten-alloyed steel seeks to increase wear resistance while maintaining a fine edge.

It is more suitable for medium and hard woods.

Swallow Steel — Tsubame

Tsubame, or Swallow Steel, is particularly geared toward working hardwoods.

Its high tungsten content gives it excellent edge retention, but also makes the steel more demanding to sharpen.

HSS steels: for the most demanding work

High-speed steels, or High Speed Steel (HSS), constitute a category of their own.

Originally developed for machining tools capable of working at high temperatures, they retain their hardness in conditions where traditional carbon steels would lose some of their properties.

For a Japanese plane, their main benefit is their very high wear resistance.

They are particularly suitable for abrasive or difficult materials:

• very hard woods;

• abrasive exotic woods;

• plywood;

• composite materials or wood-based products.

In return, sharpening an HSS blade requires more time and suitable abrasives.

SKH51: the versatile HSS

SKH51 is a Japanese high-speed steel corresponding to AISI M2. This grade is widely used for cutting tools and presents a good balance between hardness, wear resistance, and toughness.

In a Kanna, SKH51 allows for a particularly durable blade.

It is suitable for many applications, particularly for more abrasive materials.

Tsunesaburo also uses a laminated construction with a softer steel backing, which makes the blade easier to work with despite the high hardness of the HSS steel.

HAP40: powder metallurgy for the Kanna

HAP40 belongs to an even more advanced generation of high-speed steels manufactured using powder metallurgy.

Manufacturing from a very fine metallic powder allows for a particularly homogeneous microstructure and the integration of a significant quantity of alloying elements.

Hitachi classifies HAP40 among its powder metallurgy high-speed steels, with a sought-after combination of abrasion resistance and toughness.

For a Kanna blade, this translates into excellent wear resistance.

HAP40 is therefore particularly interesting for users who regularly work with:

• very hard exotic woods;

• abrasive woods;

• plywood;

• wood-based materials.

It is a steel intended primarily for edge longevity rather than ease of sharpening.

Which steel to choose for a Japanese plane?

There is no universally superior steel for a Kanna.

The right choice depends primarily on the wood being worked and your priorities.

White Steel or Blue Steel: which to choose?

This is probably one of the most frequent questions when discovering Japanese planes.

The answer essentially depends on how you work.

Choose White Steel if...

You are looking for:

• fast sharpening;

• an extremely fine edge;

• a very precise cutting sensation;

• a blade intended primarily for softwoods.

Choose Blue Steel if...

You are looking for:

• better edge retention;

• more wear resistance;

• a versatile Kanna;

• a blade intended particularly for hardwoods.

For many users, Blue Steel thus represents a particularly interesting compromise between edge quality, durability, and maintenance.

What about very hard or abrasive wood?

When you regularly work with very hard exotic woods, plywood, or other abrasive materials, HSS steels can offer a significant advantage.

SKH51 provides a robust and versatile solution.

HAP40, thanks to its powder metallurgy manufacture and very high wear resistance, is more aimed at those looking for maximum edge life.

However, it must be kept in mind that excellent edge retention usually comes with more demanding sharpening.

Steel is not the only element that makes a good Kanna

The choice of steel is important, but one must not forget the other characteristics of a Japanese plane.

The geometry of the dai, the quality of the lamination, the preparation of the ura, the heat treatment, and the quality of sharpening all have a direct influence on the plane's performance.

A good, properly prepared blade can produce an exceptional cut, regardless of the steel chosen.

Japanese planes also require precise adjustment of the dai and the blade before reaching their full potential.

In summary

Choosing a steel for a Tsunesaburo Japanese plane ultimately comes down to finding the right balance between edge fineness, ease of sharpening, and wear resistance.

White Steel favors edge fineness and ease of sharpening.

Blue Steel and Super Blue offer more wear resistance while maintaining an excellent edge.

Special steels allow the blade to be further adapted to specific species and working conditions.

SKH51 and HAP40 are aimed at the most demanding work, where abrasion resistance and edge life become priorities.

At Outinomi, we select Tsunesaburo Japanese planes and other Japanese tools by prioritizing manufacturing quality, authenticity, and consistency between the tool and its use. For example, some of our Tsunesaburo Hira Kanna are offered in White Steel or Blue Steel, depending on the model.