Improving the Appearance of Direct-Dyed Cotton Fabric with Neps through Sodium Hydroxide Pretreatments

Abstract

The effect of two sodium hydroxide pretreatments, mercerization (20% NaOH) and submercerization (14% NaOH), on the visual coverage ofneps in cotton fabric dyed with five direct dyes was examined. It was shown that direct dyes vary in their ability to achieve visual coverage ofneps in untreated cottonfabric. Treatment with either 14% or 20% NaOH before dyeing results in increased depth of shade. However, increases are greater after mercerization. There is no significant difference between mercerization and submercerization in promoting coverage of visible neps after dyeing with any of the five dyes examined. Evaluation of changes in fabric properties as a function of each treatment showed that both resulted in significant increases in fabric tensile strength and elongation as a result of fabric compaction. Effects of 20% NaOH were significantly higher than those of 14% NaOH. In addition, after mercerization, tear strength and flex abrasion were also improved.