colouring

Colouring refers to the process of adding color to materials or objects, or to the colors that result. Colouring agents include pigments, dyes, and modern colorants formulated for specific media. The field covers art and design, textiles, printing, plastics, cosmetics, and food.

In textiles, colouring often means dyeing fibers with soluble dyes that bind to the fiber, sometimes using mordants or other fixatives. Pigments are used in paints and inks where color particles are dispersed rather than dissolved. Food coloring uses approved additives to impart appearance, with safety and labeling regulations governing use.

Dyes and pigments differ in solubility: dyes dissolve in or chemically bind to the medium, while pigments remain as fine particles dispersed in the medium. Natural colorants have long been used (plants, minerals); synthetic colorants were developed in the 19th century and expanded color ranges and performance.

Colour science underpins colour matching and quality control. Colour is quantified by perceptual spaces and tristimulus values, with standards developed by organizations such as CIE. In production, colourants are formulated as concentrates or masterbatches to ensure consistency.

Safety and environmental considerations guide regulation of color additives in foods and cosmetics, and impact disposal and pollution controls for dyes and pigments used in industry.