Saminathan Ratnapandian

Textile colouration

The primary objective of colour in textiles is enhancing aesthetic appeal. In addition, colour serves diverse purposes such as identification (uniforms), warning (safety and survival vests) and mark of status (religious robes). It even marks stages of life (white wedding gowns and bereavement black, in many Western cultures) [13]. Hence, textile colouration is of great importance and has developed into an art and science [11, 14, 15]. Most textile materials acquire the desired colour(s) by the application of appropriate dyes.

1. Dyes

Dyes are complex chemicals that are absorbed by and react with suitable substrates to yield a coloured product. There are two broad dye categories based on origin, namely natural dyes and synthetic dyes. Burdett [16] credits J. W. Slater with publishing the first book in 1870 that provided comprehensive data on dyes and pigments used in textile colouration. This collection of data has gone through various stages and finally emerged as the globally recognised Colour Index (CI) published jointly by the Society of Dyers and Colourists (SDC) and American Association of Textile Chemists and Colorists (AATCC). The index scientifically classifies the wide variety of dyes based on chemical structure, colour, application methods, fastness properties, manufacturer, synthesis route and date invented [12]. Fastness properties refer to the resistance to fading of a coloured textile on exposure to different environmental conditions during its normal usable life.

1. Synthetic dyes

Present day industrial dyes are termed synthetic dyes because they are synthesised or manufactured to specifications. Raw materials used are generally petroleum derivatives. A wide range of low-cost dyes, whose properties can be modified as needed, are produced by this US$16.2 billion global industry [17]. The standardized manufacturing processes make the application methods and dyeing results repeatable and consistent [14, 15]. Consequently, high performance standards and appropriate evaluation
techniques have been developed for dyed products [18, 19]. The various synthetic dye classes shown in Figure 1.1 are briefly described below.