Use of the ultrasonic cavitation in wool dyeing process: Effect of the dye-bath temperature

Hence an experimental part of wool dyeing was carried out both to validate the previous results and to verify the dyeing quality at low temperatures (40-70 °C) in presence of US. A prototype dyeing equipment able to treat textile samples with US system of 600 W power, was used. The dyeing performances in the presence and absence of US were verified by measuring ΔE (colour variation), Re,% (reflectance percentage), K/S (colour strength) and colour fastness. The US tests performed in the temperature range of 40-70 °C were compared with the conventional wool dyeing at 98 °C. The obtained results show that a temperature close to 60 °C should be chosen as the recommended US dyeing condition, being a compromise between the cavitation intensity and the kinetics which rules the dyestuff diffusion within the fibres.