Pigment is a substance in particulate form which is insoluble in water but which can be mechanically dispersed in this medium to modify its color and light scattering properties. They are organic or inorganic colouring materials. Pigments have no direct affinity to textile fibers. They are fixed on textile materials (fabric/yarn) with the help of a binding agent in form of a this invisible coating.
In pigments auxochrome groups are absent. A number of organic pigments are prepared from dyes by combining the dyes with a dye precipitant. Pigment are abundant in nature. The cause of color is not only the light absorption of molecules but also the purely physical effect of optical diffraction at grating systems.
Pigments are applied at thickened textile pigment coating from oil-in-water or water-in-oil emulsion systems. Properties of pigments: i. It is insoluble in liquids but can be mechanically dispersed in the medium. ii. Pigments have no direct affinity towards fiber, so binding is used as a binding agent in case of pigment colouration which sticks the pigment particle on the fiber surface. iii.
Pigment are applicable to all kinds of fibers. iv. No aftertreatment is required after coloration process, only drying and curing are required. v. Only rubbing fastness of pigment colouration is poor, but water wash and light fastness are very good. vi. A wide range of bright shade can be produced by pigments. vii. In pigments auxochrome groups are absent. Differences between dyes and pigments: The difference between dye and pigment is not a clear one.
Most organic pigments are closely related to dyes with respect to their chemical structure. There are dyes which become pigments after application. Vat dye is a dye when used in dyeing, when vat dyes are oxidized and made insoluble in fabric(after vatting) that is called pigment form of vat dyes. Vat dyes act like pigment when used in printing. Now some differences are mentioned below: