The clearing of poly(lactic acid) fibres dyed with disperse dyes using ultrasound. Part 1: Colorimetric analysis

Three types of clearing processes namely water, ECE detergent and reduction clearing were used to aftertreat the dyeings of six disperse dyes on PLA fibre. Reduction clearing imparted the greatest changes to the colour strength and colour of the dyeings while treatment with ECE detergent removed surplus dye and also improved the chroma of the dyeings; treatment with water had very little effect on the colour strength and colour of dyeings, even in the presence of ultrasound. Both depth of shade reduction and colour change were greater when aftertreatment was carried out at 60 °C rather than at 50 °C due to a corresponding increase in the amount of removed dye as a result of greater kinetic energy at the higher temperature. Ultrasound neither impaired nor overly enhanced the effectiveness of either the ECE detergent or the reduction clearing processes.