Photofading of reactive dyes on silk and cotton: effect of dye—fibre interactions

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.