A dye is a colored material that forms a chemical bond with the substrate it is applied to. Dyes differ from pigments in that they do not bond chemically to the substrate they color. The dye is usually applied in an aqueous solution, and it may be necessary to add a mordant to improve the dye’s fastness on the fiber.
Because they absorb only certain wavelengths of visible light, dyes and pigments are colored. Pigments are insoluble in water, whereas dyes are normally soluble. With the addition of salt, some dyes can be rendered insoluble, resulting in a lake pigment.
Dyeing is the process of applying dyes or pigments to textile materials such as fibers, yarns, and fabrics in order to get a desired color and colorfastness. It is usually done in a specific solution that contains dyes and other chemicals. Temperature and time are critical determining elements in how dye molecules are fixed to the fiber through absorption, diffusion, or bonding. Depending on the dye, the binding between the dye molecule and the fiber might be strong or weak. Color is applied to a confined region with specified patterns in printing, although dyeing is a separate application. When dyeing a textile, it is applied to the entire surface.