The uniform distribution of particles of pigment in a printing ink vehicle, performed in the mixing and milling stages of printing ink manufacturing. Incomplete dispersion or flocculation of pigment particles is a common cause of many printing ink problems. (See Ink: Ink Manufacturing, as well as Ink: Printing Ink Problems and Defects.)
In color, dispersion refers to the separation of a beam of white light into its spectral components, caused by refraction rather than diffraction. Dispersion occurs when a beam of light passes through a transparent material (such as glass or water) at an angle; each separate wavelength that constitutes the light beam is bent at a different angle. Though not pronounced enough to be detectable in everyday surfaces (such as windows, glasses of water, or ponds), special transparent materials such as prisms can be produced which will magnify the dispersion effect rendering the full visible spectrum. Dispersion is also the cause of such phenomena in photography as chromatic aberration.