Indigo adsorption properties to polyester fibers of different levels of fineness

The dyeing behaviors using indigo vat dye on conventional and microfiber polyester and its fastness properties to washing were examined. Acid leuco dyeing technique with acetic, formic and citric acids was considered. The effect of urea addition to improve the dye build-up was also investigated. In addition, repeated multiple washings of indigo dyeings, which were compared to the results of disperse dyeings, were carried out to determine the fastness properties. From the obtained results, it is found that acid leuco form provided a satisfactory dye uptake at different pH ranges and that the improved dye build-up characteristic was achieved by urea addition due to increasing dye solubility and dye penetration within the substrates. The fastness to washing of indigo dyeings was more effective than that of comparable depth of disperse dyeings.