The colorant, or the substance used to give color to the ink, is either dye or pigmentation. Dye, consisting of small molecules, blends with the water-based solution. A water-dye based ink tints or stains the paper on a molecular level. Because the dye is composed of single molecules it lays flatter on the paper surface reflecting light more evenly and appearing more vivid. However, the smaller molecular structure of the dye-based ink also allows it to be damaged by UV light more rapidly that pigmented inks.
Pigmented colorant is insoluble. The pigment consists of much larger molecules than that of the dye, therefore the reflection of light received from a pigmented print does not appear as vibrant due to the scattering of the reflected light. The larger molecules do allow a pigmented ink's print to last substantially longer than a dye-based ink's print.
In recent years hybrid ink consisting of both dyes and pigmentation has been introduced to the market. These inks are being used in the latest line of Epson printers. The hybrid dye/pigment ink is also referred to as archival inks. The company claims that their archival inks will last twice as long as pigmented ink, close to 200 years.
In addition to the chemical base and colorant, inks also contain additives. Additives may include buffering agents for control of the inks pH levels, resin for resilience, and humectants for the prevention of evaporation. Other ingredients added to many types of ink may include fungicides, surfactants, and biocides. Each ink formula has a unique formulation of each additive, again causing dramatic differences in the final outcome.
As more research is done, we will be updating this information to let you know of the latest trends in the formulations of ink jet inks.
