A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.

A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber.

Points of DifferenceDyes Pigments
SolubilitySoluble in waternsoluble in water and most of the solvents
NumberAvailable in Large numberComparatively lesser in number
Product resistanceLower as compared to pigmentsVery high
LightfastnessLower Dyes are very much vulnerable. Lights destroy colored objects by breaking open electronic bonding within the moleculeTraditionally pigments have been found to be more lightfast than dyes
SizeDye molecules are comparatively much smaller than pigment. Dye : pigment = 1: 2000 Pigment particles are about 1-2 microns in size. It means that the particles can be seen under a magnifying glass
BondingTaking the example of dyeing a wood surface, dyed are chemicals, that have certain features called functional groups. At the level of molecules these groups serve as open pockets of electrostatic charges (+ or -). The functional group in dyes, serve as a method for attaching the dye to the woodFor examp le taking the example of a wood surface Pigment requires the help of a binder for gluing. As it is an inert substance which is merely suspended in a carrier/binder
Structure during the application processDuring application process there is a temporary alteration in the structure of the dyesDuring application, pigments have the capacity to retain particulate or crystalline structure
Imparting of ColoursDyes can only impart colour by selective absorption of the dyesPigments impart colours by either scattering of light or by selective absorption
Combustible propertiesTaking the example of a Candle making process, if the candles are dyed it is easily combustible and can be applied throughout the candleIn the example of a candle making as pigments are colored particles, they tend to clog a wick when burned. This makes them undesirable for a candle if it is colored throughout and used for burning
Chemical CompositionUsually the dyes are organic (i.e. carbon-based) compoundsPigments normally inorganic compounds, often involving heavy toxic metals
Longevity factorThe dye based printing inks do not last as long as the pigment inksTaking the case of printing inks, dye based inks offers a wide varietyIn case of ink based printing prints made with pigments lasts longer
Printing on substratesCompatible with almost all the substrates that needs to be dyedOwing to the physical makeup of the pigment inks the range for suitable substrates are limited
Colour gamut Taking the case of printing inks, dye based inks offers a wide varietyAs compared to dye-based inks, pigment inksets somewhat lags behind, on the same paper stock