A Japanese waterstone is a specific type of whetstone used to sharpen cutting tools. Waterstones are typically used to hone the edges of knives, although it can theoretically be used (with some difficulty) for any cutting edge. Most variants of the waterstone are about the size of a brick, composed of two types of sedimentary material. One side is significantly coarser than the other, and the difference between the two is noticeable by touch. Use of the Japanese waterstone dates back over two thousand years, and it’s a fair guess to assume it’s been around in some way, shape, or form since the advent of the knife tool.
Unlike other forms of whetstone, a Japanese waterstone does not require oil in order to sharpen the blade. In fact, using oil can be damaging to the longevity of the waterstone. Instead, the waterstone must be submerged in water for a few minutes prior to use to produce a softer, lubricated surface for easier sharpening. Knife honing with the waterstone can be facilitated with a nagura, a separate stone that is rubbed in a circular motion on the surface of a wet waterstone. Some of the material will rub off and create a mudlike slurry, which assists the sharpening process and provides some finish on the blade as well.
Knives are important and often expensive tools, and it’s vital to maintain a sharp edge in order to increase efficiency and reduce the risk of injuring yourself from excessive applied force on a dull blade. The process of using a Japanese waterstone is as follows:
- Submerge the stone in water for a few minutes prior to sharpening. On a side note, keeping the stone submerged in storage is a bad idea, since doing so can erode the surfaces.
- Use the coarse side first. If you choose to use one, rub the nagura stone in a circular pattern over the coarse surface until it is covered in the wet sedimentary material.
- Take your knife, and place the blade face down onto the length of the waterstone, with the edge facing away from you. Locate the bevel of the knife, which is the flat of the blade just prior to the actual edge itself. Tilt the blade so the bevel rests on the surface of the waterstone.
- With one hand holding the handle and the other steadying the blade, apply firm, even pressure and push the blade outward. Draw the blade out at the end of the motion in order to sharpen the tip of the edge. Repeat the process with a few more strokes (about three of four more times).
- Flip the knife edge over, and carefully repeat step four, this time pushing the blade the other way to sharpen the opposite side. Do this very carefully, especially if you’re pushing towards your body.
- Repeat steps four and five until the knife is sufficiently sharp. You need to keep alternating sides or you’ll end up with an uneven edge.
- Submerge the waterstone again to wash off the nagura paste. Flip the stone over to its smoother side, and sharpen the blade again for a finer honed edge. This process is necessary to even out any loose metal fibers than may be clinging to the edge of the blade from the first stage of the sharpening.
Knife sharpening is a skill that is best learned through observation and practice, so find a friend or a video to teach you before trying it yourself. Also note the material of the knife you’re using. Carbon steel holds an edge quite well and is easier to sharpen, but will rust when wet, so keep that in mind if you sharpen one with a waterstone. Stainless steel knives look pretty, but are difficult to sharpen and maintain after its manufactured edge dulls down. The best quality knives tend to be made of a composite of both, or are made of ceramic, but are often quite expensive. It’s probably a good idea to invest in a good knife anyway, whether it’s for cooking, bushcraft, or any other purpose; good quality can’t be beat, especially when you’re using a tool as potentially dangerous as a knife.