Japanese Tool Steel Explorer

KA70 vs SK85 and other steels used in Japanese tools

People searching for Japanese tool steels are usually trying to answer a specific question, such as whether KA70 or SK85 is better for secateurs, or how White Paper and Blue Paper steels compare in real use. The difficulty is that steel names alone rarely tell the full story. Japanese makers often publish steel labels that are meaningful within the tool trade, but do not always include full metallurgical specifications on retail pages.

This comparison focuses on steels as they are actually encountered in Japanese hand tools. It brings together commonly listed steels used in secateurs, shears, knives, chisels, and related cutting tools, and shows how they differ in typical hardness targets, edge behaviour, sharpening feel, and maintenance requirements. Where possible, sources are attached so the information can be checked and referenced.

Why KA70 and SK85 are often compared

KA70 and SK85 appear frequently in discussions about Japanese secateurs because both are carbon steels chosen for clean cutting and ease of sharpening. In practice, differences between tools labelled KA70 and SK85 are usually driven more by heat treatment and blade geometry than by the steel name alone. A well-treated SK85 blade at moderate hardness can outperform a harder KA70 blade if the geometry suits the task better.

For pruning green growth, many users prefer steels that balance edge stability with toughness, allowing repeated cuts without chipping. For harder or drier material, toughness and geometry become more important than absolute hardness. This is why comparing steels side by side, rather than relying on reputation alone, leads to better tool choices.

Carbon steels versus stainless in Japanese tools

Japanese tools are often associated with carbon steel, but stainless options exist and serve a different purpose. Carbon steels are typically easier to sharpen very keenly and give strong feedback on the stone, which appeals to users who maintain their tools regularly. The trade-off is basic care: wiping moisture, removing sap, and applying oil for storage.

Stainless steels reduce maintenance and are more forgiving in damp storage conditions, but can feel slower to sharpen depending on composition and heat treatment. Neither category is universally better. The right choice depends on how the tool will be used, how often it is sharpened, and how it is stored.

How to interpret hardness and performance scores

Hardness values shown here are typical target ranges rather than fixed outcomes. Two tools made from the same steel can differ noticeably if they are tempered differently or ground to different edge angles. The comparative scores are intended to highlight tendencies, not absolutes. They help explain why one steel may feel easier to sharpen, while another holds an edge longer under similar use.

If you are choosing between steels for Japanese secateurs or shears, start by matching the tool to the material you cut most often. Steel choice matters, but it should be evaluated alongside blade thickness, bevel angle, and the maker’s intended use.

Using and citing this comparison

Use the comparison tool above to select up to three steels and view them side by side. Each entry includes sources where available, so the information can be verified or cited. If you are linking to this page, consider sharing a specific comparison URL rather than the generic page, as it helps readers land on the exact steels being discussed.

Yasugi steel and Japanese paper steels

The term “Yasugi steel” is commonly used as a broad label for Japanese specialty steels associated with the Yasugi region in Shimane Prefecture. Within that tradition, White Paper (Shirogami) and Blue Paper (Aogami) are steel families rather than single fixed compositions. In simple terms, White Paper steels prioritise purity and ease of sharpening, while Blue Paper steels add alloying elements to improve wear resistance. If you want a real world reference point, see a Blue Paper No.2 example in Tobisho Aogami No.2 Damascus secateurs, and a White Paper No.2 example in Yoshioka Shirogami No.2 curved shears. Not all tools described as using “Yasugi steel” publish formal specs, which is why this comparison separates documented paper steels from retail or trade designations.

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How we source this data

This comparison is compiled from publicly available manufacturer listings, published steel tables, and reference documentation where available. When a steel is presented as a family or trade designation rather than a formal standard, this is stated explicitly and numeric chemistry is not published unless a primary source can be cited.

Hardness ranges and performance characteristics reflect typical targets used by toolmakers, not guaranteed outcomes. Individual tools can vary based on heat treatment, blade geometry, and intended use. Sources are listed for each steel entry so claims can be checked, compared, and referenced independently.