Umajiyama Tomae Whetstone 6" x 1"

Japanese name (Kanji): 馬路山 戸前 合砥石

Name breakdown:

• 馬路山 (Umajiyama / Umaji Yama) — the Umaji mine, a western Kyoto mine (Nishi Mono) located in the Kameoka district, Kyoto Prefecture, near the Ohira and Mizukihara mines
• 戸前 (Tomae) — strata designation: the fifth and most prolific working layer within the Hon-Kuchi Naori (48 seams), situated between the Senmai and Aisa layers; considered the most universal finishing strata
• 合砥 (Awasedo) — "finishing/polishing stone"; this word was previously mistransliterated as "Goto" on some stone labels and vendor listings. It is not a seam name, mine name, or any unique descriptor — it simply means the stone is an awasedo (finishing stone)

Mining region: Umajiyama is a western mine (Nishi Mono) in the Tamba/Tanba area, known for producing softer Tomae and Suita stones. Full production area address: Kyoto Prefecture, Minamikuwada district, Kameoka town, Umaji (京都府南桑田郡亀岡町馬路). The mine is closed; all current stock comes from material stored by wholesalers such as Tanaka Toishi.

Grit rating (JIS equivalent): Approximately 6,000–8,000 JIS for soft-to-medium hardness Tomae specimens. Natural stones vary considerably between individual examples.

LV Hardness: LV 2–3 (soft to medium). Umajiyama is well-documented as a mine known for producing softer Tomae stones. Confirmed individual specimens have been rated at hardness 3.5 on the 1–5 scale. At LV 2–3, the stone raises slurry quickly and easily, providing fast, forgiving performance.

Recommended progression: After a synthetic 3,000–5,000 JIS stone, or after a coarser natural stone. Functions as a finishing or pre-finishing stone. Well suited as a Kasumi polishing stage before progressing to harder finishing stones at LV 4+. Can also serve as the final stone for kitchen knives where a toothy, refined edge is preferred.

Composition: Siliceous shale (Hon-Kuchi Naori geological formation), formed under heat and pressure from marine sedimentary deposits over approximately 150–250 million years. Tomae strata stones consist of compressed silica and alumina-bearing grains bound in a clay-like matrix.

Steels to sharpen: Universal. Particularly well suited to Japanese carbon and stainless kitchen steels (hagane). Recommended for wide bevel polishing, Kasumi work, and edge finishing on a broad range of knives and tools. Suitable for both single and double bevel knives.

Usage recommendations:

• No soaking required — surface wetting only
• Stone develops self-slurry quickly after initial contact with the blade
• Feedback transitions from grippy to smooth and silky as slurry builds
• Maintain slurry on the stone surface throughout sharpening
• No nagura required in most cases due to generous self-slurry production
• Produces a hazy-to-frosty Kasumi finish; suitable as a standalone finish or as preparation for a brighter higher-grit stone
• Considered an excellent first natural stone for beginners due to ease of use and forgiving nature