Water sharpening stones

The quality of the stones.

There are different types of manufacturing processes, different types of abrasives, and different types of binders. The quality of water stones varies by brand. We can distinguish between two main types of water stones: ceramics, which are fired clays, and stones made of an amalgam compacted at high pressure.

All types of grits exist in both categories. Each manufacturing type has its advantages and disadvantages. Ceramics are harder, so they stay flat longer. But you cannot have a grit lower than 800/1000. Ceramic stones wear out diamond plates more quickly. Amalgamated water stones offer a wide range of grits. They are easier to flatten.

I have a preference for amalgamated stones for very fine grits.

Granulometry / microns.

The different grits we know (200 / 400 / 1000 / 3000 / 6000 / 8000 / 10,000) correspond to a precise micron granularity: 70 / 35 / 15 / 6 / 2 / 1.84 / 1. These different grits leave a surface condition with their corresponding finish. Depending on the finishing requirement, you will choose a specific grit.

For a striking chisel, you can very well settle for a 1000 grit. On the back of the tool (the ura), it is always better to go at least up to 3000 grit.

For finishing tools like hira kanna or tsuki nomi, it will be necessary to go at least to 6000 grit, although 8000 will always be preferable. If you want a superb finish on planing, 10,000 will be truly interesting, but you will need excellent control over the flatness of your stones.

The same goes for your kitchen knives, except that the fine grits (6000 / 8000) will leave a polished finish that will be useful not only for cutting but also for facilitating the maintenance of the knife.

The importance of sharpening flat.

It is paramount to maintain the flatness of your bevels, whether for tools or for your single-bevel Japanese knives, as sharpening consists of creating and then removing a burr. If the bevel of your cutting edge is perfectly flat, this burr will be much easier to create. This flatness also allows you to control the desired bevel angle.

Maintaining the flatness of your tools and your stones.

It is essential to preserve the flatness of your stones. To do this, you must use a diamond plate to resurface them. You should do this as often as possible. Personally, I do it after two uses of the stone. You can very easily see if your stone has lost its flatness by observing grey marks imprinted on it. Generally, beginners mainly use the center of the stone or the sides. You must avoid this by making a small path on the stone: from left to right and top to bottom.

Diamond plates, their functions.

Today, many people use diamond plates to sharpen their tools directly. I advise against this use, especially on carbon blades. Diamond is too abrasive for carbon. You will leave deep scratches beyond the plate's grit. However, you can use a low-end diamond plate (but one that is very flat, you must check this) to true up a badly damaged back. This is useful for restoration... The Atoma brand is a benchmark in Japan. These plates are manufactured with a specific process that offers excellent surface homogeneity. The diamond grits are laid flat and the surface is very regular. They have the same feel as shagreen.

https://outinomi.com/products/plaque-daffutage-diamantee-grain-600-atoma-de-remplacement

Rigid supports for your stones.

It is necessary to rigidify your stones. Traditionally in Japan, natural stones are glued onto a wooden base. This support has several advantages. First of all, it allows you to rigidify the stone, and this is really interesting as the stone becomes thinner. When the support is thick or raised, it provides comfort and clearance for certain tools. I will return at greater length to the interest of a stand (support to secure the stone) and the proper posture for sharpening in a dedicated blog post.