Chinese invented the ink stone. They needed a smooth flat surface to grind the ink stick into liquid ink and to this purpose they created an ingenious grinding tool -the ink stone.
The oldest ink stones were made out of pottery. By the 7th century Chinese had managed to produce a ceramic ink stone that could hardly be distinguished from a natural stone, the impressive Chengni ink stone -not even a knife could scratch its surface. But its manufacturing was extremely arduous and they gradually replaced them with natural stones.
For centuries Chinese and Japanese have searched for the perfect natural stone and have created a fascinating ink stone culture with famous legendary ink stones.
How to choose an ink stone for Japanese calligraphy
The most important part of an ink stone is the flat surface on which you grind the ink stick with a little bit of water. This surface must have the right hardness and texture. When you touch it you should feel a polished surface and it should have a satiny sheen.
A high quality ink stone produces fine thick ink quickly. If the ink stone is too soft, the ink stick will not adhere to the ink stone and it will take very long to grind the ink. On the other hand, if the ink stone is too hard it will produce a coarse grained ink that is not homogeneous.
If an ink stone is too rough it can damage the very delicate hairs of the brush, because you use the surface of the ink stone to bring the tip of the brush into the right shape or to remove the excess ink. In short, an ink stone should be neither too hard nor too soft.
As I said, an ink stone must also have the right texture or porousness. If it is too absorbent the ground ink dries immediately. To ascertain that an ink stone has the right degree of absorption you can blow on its surface. It your breath dries immediately the ink stone is not very good.
What is the best shape and size for an ink stone
An ink stone can be round or rectangular; its shape makes no difference for the grinding, but you might have your own preferences. I myself prefer the rectangular ink stone when grinding a lot of ink. This ink stone has a flat surface where you grind the ink and a small reservoir at the other end for the ground ink. Thus you avoid having the ink stick in water for too long.
The best size is the one that makes you feel at ease when describing the circular movements with the ink stick on the ink stone. For regular calligraphy practice I recommend a round ink stone with a diameter of about 5″ or 13 cm or a rectangular one of about 6″ or 15 cm in length. With this size you do not feel constraint by a too small grinding space, and you can make enough ink for one calligraphy session.
There are very small ink stones for traveling. Usually they are part of a Japanese calligraphy set; they may not be the best quality but it is great to have them at hand when you feel inspired far from home.
For the practice of Zen calligraphy you need an ink stone of at least 13″ x 8″ or 30 x 20 cm; it weighs several pounds. This ink stone has a real physical presence; the grinding surface is large and it has a deep well that can collect the sufficient amount of ink to brush large calligraphies.
How to take care of a Japanese ink stone
As a rule you grind the ink you need for the calligraphy session you planned for that same day. Keep in mind that you should never let the ink dry inside the ink stone, because it can damage it permanently. The ink sticks to the stone and it is very difficult to remove it, because if you scrape the surface too hard, you can also damage the stone.
If you decide to use bottled liquid ink and put it into the ink stone, you should be even more careful not to let it dry. The liquid ink has a lot of glue and when it dries it virtually embeds itself in the surface of the stone. If this happens the stone is spoiled irreparably and you cannot use it any more for grinding an ink stick. Do not use a valuable ink stone as a container for bottled ink.
A lid on the ink stone is very useful to prevent the ink from drying, especially recommended in hot summers. You can also use the cover of the wooden box that protects the ink stone.
You should always clean the ink stone after using it. Wash it thoroughly with fresh water. You can use a soft sponge, but never use a metallic or a hard cloth because you can damage the stone.
For the grinding of mineral colors for sumi painting I recommend ceramic ink stones or plates, or the cheaper natural stone ink stones because mineral residues may damage the more valuable stones.
Regarding external protections superior ink stones are sold well protected in a wooden box. As a rule, the more valuable the ink stone, the worthier is the box.
Chinese or Japanese ink stone?
For beginners a cheaper Chinese ink stone will do. You can easily find them on the market. If you are a more advanced calligraphy practitioner you will need a genuine ink stone to enhance the performance of the ink.
When buying an ink stone you should check it to make sure that it has the two qualities I described above. Depending on your personal preferences for the Chinese or Japanese aesthetics you can choose between various natural stones from which the ink stones are made.
The Chinese and Japanese ink stone tradition.
China has very old rock formations which make excellent ink stones. Japan is geologically younger, but it nevertheless has several natural stones that are suitable for superior ink stones for Japanese calligraphy.
The Chinese Duan and She are two legendary ink stones which have been prized since ancient times and are still highly in demand.
The best Duan stone is carved out of the rock formations of the lower parts of the mountain. These stones have long been immersed into the water, have a very fine grain and are very smooth. But these Duan ink stones with their unique purplish color and perfect softness are not available anymore. Collectors search after them as if they were gold; you can admire these priceless antique Duan ink stones in museums or private collections.
Current Duan ink stones come from the higher or middle parts of the mountain. They are still the best ink stones and therefore expensive. You can recognize them by their purplish blue color, which gives them the noble nature of the Duan ink stone. Their surface is perfectly smooth and they produce a consistent homogeneous ink quickly.
The second most renowned is the She ink stone, with a bluish-black color. The She stone is both harder and smoother than the Duan ink stone, but it also produces a very good ink stone.
In Japan the Akama is highly regarded. It is a black or reddish-black ink stone, quite hard but smooth enough to produce excellent ink.
The Ogatsu is a very noble Japanese ink stone. Its color is either black or deep indigo and it has a beautiful shine and perfect hardness.
But it is still rather difficult to find high quality Japanese ink stones on the Western market, which I hope will change in the near future.
All these ink stones have a perfect smoothness and produce excellent ink. They are expensive but it is a lifetime investment that will give you a very deep satisfaction.