The color of ink is dictated by tiny particles called pigments. Pigments can be chemicals that are either insoluble in water and only slightly soluble in solvent, soluble in water and solvent, and lacquers which are created by fixing a coloring agent on powdered aluminum. The size and shape of the particles of the pigment define the refractive value of the ink, its depth and hue. More particles of pigment means a denser, more vivid color.
The coloring ingredients must be suspended within a liquid to keep them stable and pass them onto the print medium with accurate color. Ink vehicles are a vegetable base, such as linseed, resin, wood oil, or a solvent derived from kerosene. Vegetable base vehicles dry by penetration and oxidation. Solvents dry by evaporation.
Additives stabilize the ingredients within ink and help ink dry properly.