Pigment - What is a pigment?
A type of colourant; pigments alter the colour of other materials because they selectively absorb different wavelengths of light. The colour a pigment produces is determined by the particular wavelength(s) of light that are transmitted or reflected by the pigment, and not those that are absorbed.
Pigments are usually distinguished from dyes in two ways; pigments do not have an affinity for the substrate to which they are applied (there is no attraction between the two) and they are insoluble (they do not dissolve in a solvent, instead they are suspended in the solvent). They are a dry colourant that is ground into a fine powder made up of small particles; this powder is then suspended in a vehicle or added to a binder, which allows the pigment to be transported as required and provides adhesion so the pigment can adhere to a substrate.
Pigments can be natural (including earth and mineral pigments and biological pigments taken from animals and plants) or synthetic; pigments were made synthetically as early as 2BC but were only developed industrially in the 18th and 19th centuries. Most pigments are organic, as these tend to produce brighter and stronger colours than inorganic pigments.
In labelling, pigments are used to make coatings for face materials that are to be used to make labels (where they determine a variety of characteristics such as colour, brightness, whiteness, opacity, surface smoothness, and printability) and as the colourant in some printing inks, where they sit on top of the face material and impart a number of important properties including transparency or opacity, and resistance to heat, light, chemicals, water, and oils.Go Back to Glossary