墨

(RO: sumi; PR: "soo-mee")
The ink used by calligraphers.

It is made from a mixture of soot particles and glue. This mixture is dried into sticks of solid ink which can be rubbed in water to produce liquid ink. Pre-made liquid ink is also widely available, and because rubbing solid ink sticks is time consuming, liquid ink is used for most calligraphy practice these days.