Asano Mikawa Nagura - Botan, Betsu-jo #87SD342n765

Classification
Type:  Asano Mikawa Shiro Nagura (純三河白名倉).
Stratum/Layer: Botan (ボタン) — the initial, fastest-cutting stage in the traditional Mikawa razor/blade honing progression.
Grade/Stamp: Betsu-jo (別上) — "Superior Selected" grade, indicating uniform grain consistency and lack of toxic inclusions.
Inspection Seal: Red oval Ken-Asano (検 浅野) stamp verifying authentication and quality testing.
Physical Characteristics & Evaluation
Weight & Dimensions:  Approx.: 70mm x 50mm x 26mm Weight: 190g
Shape & Preparation: Clipped block/tapered trapezoid format with chamfered edges on the stamped face, preventing chipping during slurry generation.
Purity & Pattern: Clean, chalky-white with some grey specs and benign suji lines, free of any toxic inclusions. 
Condition: Excellent, lightly chamfered, with crisp, fully intact stamps.

Functional Description
Abrasive Action: Botan is the fastest-cutting slurry stone among the standard Mikawa layers. It releases a creamy, milky-white slurry that quickly cuts steel and establishes a clean scratch pattern before transitioning to finer stages like Tenjyou, Mejiro, or Koma.
Applications: Excels at building fast-cutting slurry on hard finishing bench stones (Awasedo/Tomae), breaking in fresh stone surfaces, refining razor bevels, and establishing soft, even kasumi base finishes on bevels and clad steels.