Dyeing of pashmina wool using Butea monosperma flower extract

Abstract

Pashmina wool has been dyed with natural dye extracted from flowers of Butea monosperma using an aqueous method,
and its optimization is done by response surface methodology. The scoured wool is mordanted with tannic acid and dyed
with the aqueous extract of natural dye. The dyebath parameters have been optimised by varying concentration, temperature,
and time in the range of 10–30%, 50– 90o
C, and 40–80 min respectively. Box-Behnken response surface methodology is utilized to standardise the process parameters. The dyed samples are evaluated for colour strength (K/S), wash fastness, and light fastness. The maximum and minimum K/S, achieved after dyeing, are 3.41 and 1.31 respectively. The wash fastness performance of the dyed samples shows high colour change, however the staining on adjacent wool and cotton is found minimal. Light fastness rating is found good to moderate and considered to be within the permissible limits. The statistical model suggested by RSM is found significant, with a P value of less than 0.05 and an F value of 39.2, and validated by performing selected experiments of high desirability. The results of the predicted and experimental K/S are found very close. This study indicates the potential increase in the use of natural dyes in indigenous pashmina wool varieties.