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Brand: Tanaka Toishi 田中砥石工業所.
Producing Area:  Kyoto/ Japan
Mine: Kouzaki
Appearance: Certainly a base of blue, hence the name "Ao"-to, "blue" stone. These softer versions tend to have a tint of red/brown to them, a decent indication of their softness level.
Size: 175mm x 52mm 54mm
Weight: 1031g
Grit Range: ~2000

1-5 Scale: 1 = Less, 5 = More

Hardness Level: 2
Scratch Depth: 4
Speed: 4
Wear Rate: 3.5
Self Slurry: 4.5
Thirst: 3
Consistency: 5
Feedback: 4
Ease of Use: 4

Recommended Usage: Early/mid polishing sequence, hazy Kasumi, textured edges with solid bite.

Notes: This is slightly coarser and softer vs. its finer and harder Aoto sibling. These softer versions will be faster cutting, create more slurry, leave slightly deeper scratches, create darker/hazier Kasumi, and would be used earlier in a polishing progression. Softer stones tend to be easier to use as they are more "forgiving" than harder stones, thus easier to learn on. These are "true" Aoto of quality, consistency, and provenance. Given their price they are an awesome way to get involved with natural stones. 

Disclaimer: Given the natural aspect of these stones, all subjective qualities are our estimates and may vary slightly from your exact expectations and assessment. The images shown and characteristics described may be from a previous example. If purchased, yours may differ slightly in appearance, weights and measures, and qualities. Stamps may be different or not present, especially if it has been tested.

Brand: Tanaka Toishi 田中砥石工業所.
Producing Area:  Kyoto/ Japan
Mine: Kouzaki
Appearance: Certainly a base of blue, hence the name "Ao"-to, "blue" stone. These softer versions tend to have a tint of red/brown to them, a decent indication of their softness level.
Size: 205mm x 57mm x 55mm
Weight: 1430g
Grit Range: ~2000

1-5 Scale: 1 = Less, 5 = More

Hardness Level: 2
Scratch Depth: 4
Speed: 4
Wear Rate: 3.5
Self Slurry: 4.5
Thirst: 3
Consistency: 5
Feedback: 4
Ease of Use: 4

Recommended Usage: Early/mid polishing sequence, hazy Kasumi, textured edges with solid bite.

Notes: This is slightly coarser and softer vs. its finer and harder Aoto sibling. These softer versions will be faster cutting, create more slurry, have deeper scratches, create darker/hazier Kasumi, and would be used earlier in a polishing progression. Softer stones tend to be easier to use as they are more "forgiving" than harder stones, thus easier to learn on. These are "true" Aoto of quality, consistency, and provenance. Given their price they are an awesome way to get involved with natural stones.  

Disclaimer: Given the natural aspect of these stones, all subjective qualities are our estimates and may vary slightly from your exact expectations and assessment. The images shown and characteristics described may be from a previous example. If purchased, yours may differ slightly in appearance, weights and measures, and qualities. Stamps may be different or not present, especially if it has been tested.

Brand: Tanaka Toishi 田中砥石工業所
Dimensions: 225mm x 86mm x 44mm
Weight: 1615g

Notes: Really nice specimen from the famous Mikawa mine in Aichi Prefecture via the famous Tanaka Toishi brand. They are firm to hard, and quality specimens are fast and give good polishing results. Generally easy to use depending on the hardness.

Suggested Use: pre or final polisher for knives and push-cut tools.

Background Info: Nagura is made of lithified tuff, which is silica-rich stratified volcanic ash that has been compacted into a solid over many, many years. They contain very fine particles of silica (and other  which are often more friable than other sedimentary stones, and thus are ideal for polishing. They are used as one of the last stones before Uchigumori in a traditional sword polishing sequence. The word "Nagura" is the named after the individual who discovered the utility of the lithified tuff as a whetstone, Sakon Nagura, over 700 years ago.

Please Note: Given the natural aspect of these stones, all subjective qualities are our estimates and may vary slightly from your exact expectations and assessment. The images shown and characteristics described may be from a previous example. If purchased, yours may differ slightly in appearance and qualities. Dimensions, weight, and stamps may be different from listed if it has been tested.

Brand: Tanaka Toishi 田中砥石工業所
Producing Area: Mikawa Mountain Range, Kitashitara, Aichi - Japan
Mine: Kada Mountain or unspecified Junmikawa stratum
Strata: N/A
Appearance: "Striped" (shima) lines running linearly down the length of the stone, a mix of off-white and orange. Beautiful chalky block!
Size: 220mm x 82mm x 45mm
Weight: 1573g
~Grit Range: 2500-4000

1-5 Scale: 1 = Less, 5 = More
Hardness Level: 3.5
Scratch Depth: 2.5
Speed: 2 (4 with tomo nagura)
Wear Rate: 2
Self Slurry: 2 (4 with tomo nagura)
Thirst: 3
Consistency: 3.5
Feedback: 2.5
Ease of Use: 2.5

Notes: A large, pure nagura that will last many years. 

Suggested Use: pre or final polisher for knives and push-cut tools.

Background Info: Nagura are made of lithified tuff, which is silica-rich stratified volcanic ash that has been compacted into a solid over many, many years, and this composition yields unique sharpening and polishing properties. Much of their use has been centered around blades other than knives: swords, razors, woodworking tools and so on. Nagura can come from several locations in Japan, the most famous being the Junmikawa (Mikawa) mine located within the Mikawa Mountain range in Aichi Prefecture. 

Chu Nagura are used as one of the last stones before Uchigumori in a traditional sword polishing sequence. Such "proper" Chu Nagura are mined at Kada Mountain, not from the Mikawa mine-proper, both of which are in the same mountain range. Chu Nagura can also be somewhat of a catch-all term for stones from the Mikawa mine that do not fit cleanly into the known classified strata. Within swords, "chu" is often used to roughly mean "medium" (medium grit, medium size, etc.)

Please Note: Given the natural aspect of these stones, all subjective qualities are our estimates and may vary slightly from your exact expectations and assessment. The images shown and characteristics described may be from a previous example. If purchased, yours may differ slightly in appearance and qualities. Dimensions, weight, and stamps may be different from listed if it has been tested.