Inksticks (Chinese: 墨 Mò; Japanese: 墨 Sumi; Korean: 먹 Meok) or Ink Cakes are a type of solid ink (India ink) used traditionally in several East Asian cultures for calligraphy and brush painting. Inksticks are made mainly of soot and animal glue, sometimes with incense or medicinal scents added. To make ink from the inkstick, it has to be continuously ground against an inkstone with a small quantity of water to produce a dark liquid which is then applied with an ink brush. Artists and calligraphists may vary the thickness of the resulting ink according to their preferences by reducing or increasing the intensity and time of ink grinding.
The earliest artifact of Chinese inks can be dated back to 12th century BC, with the use of charred materials, plant dyes and animal-based inks being occasionally used with mineral inks being most common. Mineral inks based on materials such as graphite were ground with water and applied with ink brushes. Indeed, the mineral origins Chinese inks were discussed by Eastern Han scholar Xu Shen (許慎, 58 CE – ca. 147 CE). In Shuowen Jiezi, he wrote "Ink, whose semantic component is 'earth', is black." (墨，從土、黑也), indicating that the character for the ink ("墨") is composed of black ("黑") and soil ("土") due to the earthly origins of the dark mineral used in its production.
The move from using graphite inks to soot and charred inks occurred prior to the Shang dynasty. From studies of ink traces from the artifacts from various dynasties, it is believed that the inks used in Zhou dynasty are quite similar to those used in the Han dynasty. However these early inks, up to the Qin dynasty, were likely stored in liquid or powder forms that do not preserve well and thus their existence and constitution can only be studied from painted objects and artifacts. Physical proof for these first "modern" Chinese soot and animal glue inks were found in archaeological excavations from tombs dated to the end of the Warring States period around 256 BC. The ink were formed by manual labour into pellets, which were ground into ink on top of a flat inkstone using a smaller stone implement. Many pellet-type inks and grinding implements have been found in Han tombs with the large ingot-types inks appearing in late Eastern Han. The latter inks have physical markings which indicate that kneading was used in their production.
One of the first literary records of inkstick production in China is from qimin yaoshu (齊民要術) written during Northern Wei. Elaboration of the techniques, technical requirements, and ingredients were also noted in scroll ten of yunlu manchao (雲麓漫鈔) and the "ink" chapter of tiangong kaiwu (天工開物), the notable Ming dynasty encyclopedia by Song Yingxing (宋應星).
In general, inksticks are made with soot and animal glue, with other ingredients occasionally added as preservatives or for aesthetics:
- Soot: Soot is produced by anoxic burning of oils such as tung oil (桐油), soybean oil, tea seed oil, and lard, or from wood such as pine.
- Animal glue: Egg white, fish skin, or ox hide glues are used to bind the inksticks together
- Incense and medicines: To improve the physical aesthetics of the inkstick, incense and herb extracts from Traditional Chinese medicine such as cloves, comfrey, ash (Fraxinus chinensis) bark, sappanwood, white sandalwood, Oriental sweetgum, or even deer musk and pearl dust were added. These ingredients may serve as preservatives for the inkstick.
The ingredients are mixed together in precise proportions into a dough and then kneaded until the dough is smooth and even. The dough is then cut and pressed into a mold and slowly dried. Badly made inksticks will crack and craze, due to inadequate kneading, imprecise soot to glue ratio, or uneven drying.
The commonest shape for inksticks is rectangular/cuboid though other shapes are sometimes used. Inksticks would often have various inscriptions and images incorporated into their design, sometimes giving idication of who the maker is, the name, some poetry, the type of inkstick and/or an artistic image.
A good inkstick is said to be as hard as stone, with a texture like a rhino and be black like lacquer (堅如石，紋如犀，黑如漆). The grinding surface when reflected with light should be of a blueish-purple sheen if good, black if not so good and white if bad. The best inksticks would make very little noise when grinding due to the fine soot used which makes the grinding action very smooth whereas a very noisy or scratchy grind would indicate an ink of poor quality with a grainy soot. The inkstick should not damage or scratch the inkstone when grinding otherwise it is inferior.
There are many types of inksticks that are produced. The artist or calligrapher may use a specific ink for a special purpose or to create special effects.
- Oil soot ink: made using the soot of burnt tung or various other oils. There is more glue in this type of ink than the other kinds so does not spread as much. Gives a warm black colour. It is good as a general purpose painting and calligraphy ink.
- Pine soot ink: made from the soot of pines. Has less glue so spreads more than oil soot inks. Gives a blueish-black colour. It is good for calligraphy and meticulous style painting.
- Charcoal ink: made using standard wood charcoal. It has the least amount of glue and so spreads on paper more than other inks. Mainly used for freestyle painting and calligraphy.
- Blueish ink (青墨): oil or pine soot that has been mixed with lacquer soot to produce a subtle blueish-black ink. Mainly used for calligraphy.
- Coloured ink: oil soot ink that has been blended with pigments to create a solid ink of colour. Most popular is cinnabar ink which was reportedly used by emperors.
- Medical ink: ink produced by mixing standard ink with herbal medicines which can be ground and taken internally.
- Collectors ink: ink that is highly decorative and in odd shapes that are meant for collecting rather than actual use.
- Custom ink: ink that has been commissioned by an artist who may want a specific type of ink to suit their needs.