An ink consists of a liquid base and a pigment, or dye. The pigment provides a colored residue that sticks to a surface when the liquid dries. The first inks were invented by the Chinese some 4,500 years ago, made from a mixture of soot, lamp oil, gelatin (from animal skins), and musk (to counteract the smell of the oil). The ink was used to blacken the raised surfaces of stone carvings to emphasize shapes and letters. Later, in China and elsewhere, more reliable inks were developed using powdered minerals, plant extracts, and berry juices as pigments.
With the advent of writing, and of papyrus and then paper, new types and colors of ink were required for use with writing implements designed for detailed and permanent texts. Some 2,500 years ago, the Chinese developed a solid ink to be stored as a stick; such inks are still in use today. When required, ink is simply scraped off the stick and mixed with water
Other early ink recipes included metal dyes, seed husks, and the ink of cuttlefish (yielding a deep brown ink known as sepia). One enduring recipe, invented some 1,600 years ago, consists of iron salts, tannin (from tree galls), and thickener. This ink is a blue-black color when first used but fades to brown over time.
With the arrival of the printing press in the fifteenth century a different sort of ink was required to stick to printing blocks. A thick, oily ink made from soot, turpentine, and walnut oil was developed specifically for printing. Modern inks are complex fluids, consisting of varying amounts of solvents, pigments, dyes, resins, lubricants, and other materials.
