What is sumi ink?

Sumi ink is a type of ink traditionally used in calligraphy, brush painting, and sumi-e, a form of Japanese ink painting. It is made from soot, oil, and water, and is prized for its rich, deep black color and subtle variations in tone. Sumi ink is typically applied with a brush onto absorbent paper or silk, and is used to create precise lines and expressive brushstrokes. It is popular among artists and calligraphers alike for its versatility, durability, and unique aesthetic qualities.