Aogami #1 (Blue Paper Steel No. 1) is a premium high-carbon Japanese steel that sits between Aogami #2 and Aogami Super in terms of performance. It is designed for professional-grade tools where edge retention and hardness are the top priorities.
Like the rest of the Blue Paper series, it is a non-stainless steel that requires careful maintenance.
Key Characteristics
Higher Hardness: Due to its increased carbon content compared to #2, Aogami #1 can be heat-treated to a higher hardness, typically between 62–64 HRC.
Superior Edge Retention: The higher levels of Carbon and Tungsten create more hard carbides. This means it will stay sharp significantly longer than Aogami #2 or Shirogami (White Steel).
Exceptional Sharpness: Despite the extra alloys, it maintains the high purity characteristic of Japanese steels, allowing it to achieve a "laser-like" edge that is much keener than most Western stainless steels.
Brittleness: The trade-off for the higher hardness and edge life is that Aogami #1 is more brittle than Aogami #2. It is more prone to chipping if used on hard materials or subjected to lateral stress.
High Reactivity: It has very little chromium (only for stability), so it will rust almost immediately if left wet. It will develop a dark patina very quickly when cutting meat or acidic vegetables.
Chemical Composition
Aogami #1 is a "boosted" version of the #2 formula:
Carbon (C): 1.25% – 1.35% (Higher than #2’s 1.10% for increased hardness).
Tungsten (W): 1.50% – 2.00% (Increases wear resistance and edge life).
Chromium (Cr): 0.30% – 0.50% (Increases hardenability and wear resistance).
Manganese (Mn): 0.20% – 0.30%
Common Applications
Professional Japanese Kitchen Knives: Preferred for high-end Gyutos, Yanagibas (sashimi knives), and Honesukis where the chef wants a longer-lasting edge for high-volume work.
Precision Woodworking Tools: High-quality Japanese chisels and plane irons.
Custom Knives: Favored by Japanese master smiths who want to showcase their ability to heat-treat complex, high-carbon alloys.
Aogami #1 vs. Aogami #2
Aogami #1: Better edge retention and higher hardness, but more difficult to sharpen and more prone to chipping.
Aogami #2: More toughness and easier to sharpen; considered the "all-rounder" for most users.
Aogami #1 vs. Aogami Super
Aogami Super adds Molybdenum and Vanadium, making it even more wear-resistant and slightly tougher than #1, but many traditionalists prefer the "purer" feel of #1 on the sharpening stones.