There are many methods of sharpening tools ranging from carbide draws, diamond plates, ceramic rollers and rods, synthetic sharpening stones, or sharpening steels. We use Japanese natural whetstones to finish the edges of all our cutting tools. Not only are they beautiful in appearance and enjoyable to work with, but when used properly, Japanese natural whetstones will produce and retain an edge that will outperform all of the sharpening methods mentioned above. Some well accepted advantages of using natural stones include:
- Minimal burr formation during sharpening
- Stabilization and increased toughness of cutting edge
- Finer edge achievement upwards of 30000 grit equivalent
- Uneven particle size produces micro-serrations increasing edge retention
- Minimal removal of material therefore increasing the life of the tool
Currently, we use several stones with different characteristics from mines including Nakayama (中山), Okudo (奥殿), Shoubudani (菖蒲谷), Shinden(新田), Okunomon (奥ノ門). Our stones are maintained using atoma diamond plates and for some sharpening applications, we also dress our stones using Asano stamped mikawa and other special koma naguras to improve honing. We pride ourselves in providing an outstanding level of sharpness for all our tools.
Japanese whetstones are mined from several mountains throughout Japan from different strata. The strata can indicate the depth from which the stone was quarried. Generally speaking, the deeper strata contain harder stones and every stone will have different sharpening properties. Softer stones are usually well suited for kitchen knives while harder stones, although more difficult to use, are more suitable for razors and chisels. These sedimentary stones formed around 70 million of years ago and contain fine silicates such as chert, silicon dioxide, and clay binders such as feldspar and sericite/muskovite. The ratio of silicates to binder along with other trace elements (such as iron oxide) largely dictates the sharpening properties of the natural stones.
Nagura, translating to “correction” in English, are smaller whetstones that are often rubbed on the surface of larger Japanese natural stones to increase the initial slurry on the whetstone surface. They also vary in composition, particle size and hardness to compliment the main whetstone. When used together one can experience increases in cutting speed, flatten irregularities in the stones surface while unclogging metal particles (swarf) from previous sharpening sessions that may be trapped in the surface pores of the stone.