SK4 Carbon Steel vs Shirogami #1

A standardized Japanese Industrial Standard (JIS) carbon tool steel. Slightly higher carbon than SK5 and lower than SK2, making it one of the most balanced general-purpose tool steels in the JIS classification. Widely used for saw blades, knives, and hand tools where consistent heat treatment and predictable performance matter more than ultimate edge retention.

Pure high-carbon steel with minimal impurities. Takes a laser-like edge and is easy to sharpen, but more brittle than Aogami. The traditional choice of master woodworkers who demand the finest possible cutting edge and sharpen their tools with religious dedication. Rust forms overnight if neglected.