Maruo Shiki Uchigumori

Size (mm) / Weight

210x78x40 / 1,563g

Performance

Hardness / Fineness: 3- / 4-

This stone is soft, easy going and generally extremely pleasurable to work with. While not fine enough to serve as a finisher for razors or tools, it certainly could function as a one-stop-shop for knives. It will self slurry under moderate pressure on wide-bevel. It has exceptional tactile feedback that is both grippy enough to provide informative feel and creamy enough to feel smooth in all situations. The stone is very clean and I see no lines or su nests that give me any reason to thin the entirety of the stone won't be perfectly usable. Due to the friability, there is good engagement for sharpening and high speed. This is suitable for final sharpening of kitchen knives and pre-finishing for razors and tools. 

A matte, high-contrast kasumi finish is easily achieved. While maximum detail won't be available, this stone will work well with all low-alloy steels, including honyaki, and will provide an easy, no-fuss solution for kasumi polishing. In a progression, it could easily handle the transition from higher grit (3k - 6k) synthetics to natural stones and serve as a bridge to the finest awasedo. If you are new to polishing or looking for a one and done solution for kasumi, this is my recommendation. 

Aesthetics & Other Notes

The stone has grey-blue and yellow-green base coloring with sparse red renge and golden lines throughout. The golden coloration is all color and doesn't effect feel or performance at all. The stone is very consistent. 

I must call out that the bottom of this stone is rather uneven. I would go so far as to say that the bottom 5mm, should you ever sharpen through 35mm of natural stone (extremely unlikely outside of a professional carpenter or polisher), will be rather oddly shaped and maybe not suitable for applications beyond finger-stones. 

This stone is sealed. The top-surface stamps have been lapped off as part of preparing the stone for testing and use. The side stamps remain untouched.

Maruo (丸尾山, Maruoyama)

One of the few that continues to be operational, this Western mine is renowned for its soft shiro suita. This mine is also well regarded for its shiki uchigumori (tenjyou suita), ao suita, and aisa-layer stones. Once widely available and relatively cheap, increased demand has outpaced supply making these stones harder to get and more expensive than just a few years ago. All things considered, however, they are comparatively still quite attainable.