India ink has been used for writing and drawing for more than 2,000 years, and is still used today by professionals ranging from artists to microbiologists. The ink was originally made out of black pigments procured from India, hence the name, and is still produced using the same three essential ingredients.
The original black carbon pigment in India ink was made from blackened soot, burnt bones, tar, pitch or other black material. The finest ink came from the very finest soot, or lampblack. Modern India ink is usually made from black carbon from burnt wood and resin, very similar to the ancient method. One variant of India ink is a warm brown pigment called "bistre," made from the burned oil extracted from the soot of burnt wood—often beechwood. Bistre is also popular with artists because it has the same semi-permanent qualities of India ink, but produces a rich sepia tone instead.
Water is the main liquid component of India ink and suspends the individual carbon pigment particles. Artists might add more water to the ink to dilute the pigment and produce a range of gray and black tones, also known as washes. This style of gray-on-black art is popular in Asian inked art, particularly Japanese sumi-e.
Waterproof binding agents include varnish, gelatin, glue and shellac. The main purpose of the binding agent is to prevent the ink from bleeding during later watercolor washes after it has had time to cure and dry. Acrylic binders are waterproof as well, but may take as long as 24 hours to fully cure and dry. Most waterproof India inks are acid-free and non-corrosive to paper and other materials over time. Non-waterproof India ink contains vegetable gum as a binding agent and is both opaque and archival, meaning that it will not degrade from exposure to light.