Wool fabrics were treated with atmospheric pressure helium glow discharge plasma in an attempt to improve felting and dyeing behavior with cold brand reactive dyes using cold pad-batch method at neutral pH. On glow plasma treatment, the hydrophilicity of wool surface and its resistance toward felting was greatly improved without any significant damage to the cuticle layer. The color strength of the plasma treated dyed wool on the surface (in terms of K/S) was found to be nearly double of the color strength of dyed untreated wool fabric. However, the corresponding total dye uptake of the treated wool increased by a much lower value of 40%-50%. The reason behind this altered dyeing behavior was investigated by studying the dye kinetics using infinite bath and surface characteristics using SEM and SIMS. It was found that the glow plasma treatment greatly transformed the chemical surface of the wool fibers. It resulted in uniform removal of hydrophobic cuticular layer, which resulted in better diffusion of the dye molecules into the fiber, and formation of hydrophilic ANH 2 groups near the surface, which helped in anchoring the dye molecules close to the surface giving higher color strength than expected.

Fading characteristics of selected bifunctional and monofunctional reactive dyes have been studied on silk and cotton. Dyes were applied in the reactive and hydrolysed forms in order to study the influence of covalent bonding on the photofading of reactive dyes. The active dye-fibre interaction was found to influence the light fastness of dyes. Reactive dyes forming covalent bonds exhibited better fastness especially on cotton. Only a slight difference in light fastness of fixed and unfixed dyes was observed in the case of silk. The bifunctional reactive dyes, due to the formation of crosslinks, maintain the integrity of the fibre particularly for short periods of light exposure.

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The roots of Arnebia nobilis have traditionally been used as a colorant in food and cosmetic preparations. The deep red colour obtained is attributed to the presence of shikonin and its isomer alkannin and their derivatives. In this study, five colouring components were extracted from the roots of A. nobilis. These were separated and purified chromatographically and characterised using various spectrophotometric techniques. Three of the five components were identified. The major component was found to be alkannin β, β‐dimethylacrylate [5,8‐dihydroxy‐2‐(1′‐β, β‐dimethylacryloxy‐4′‐methylpent‐3′‐enyl)‐1,4‐naphthoquinone], accounting for nearly 25% of the total colouring matter. Alkannin acetate [2‐(1′‐acetoxy‐4′‐methylpent‐3′‐enyl)‐5,8‐dihydroxy‐1,4‐naphthoquinone] made up ca. 8% and shikonin [(5,8‐dihydroxy‐4′‐methylpent‐3′‐enyl)‐1,4‐naphthoquinone] contributed ca. 6% of the colouring matter. Polyester was dyed pink, nylon was dyed blue and all other substrates acquired a purple hue under similar dyeing conditions. The dyed fabrics showed excellent wash, rub and perspiration fastness; however, light fastness was found to be poor.