Enzymatic anti-felting finishing of the dyed woolen textiles through the collaborative action of mild reduction and protease treatment

Proteases have emerged as promising agents for wool anti-felting finishing due to their eco-friendly characteristics. However, while natural proteases are used to hydrolyze the scale layer, their tendency to penetrate into the interior of the fiber often leads to undesirable consequences, including unacceptable damages, and reduced color depth of the dyed textiles. To address these limitations, a combined approach involving mild reduction treatment and controlled protease incubation was developed. This strategy specifically targets the reduction of adverse effects associated with protease treatment, particularly irreversible fiber damage and dye leaching. Specifically, a sodium bisulfite pre-reduction was employed to loosen the highly cross-linked scale layer in dyed wool, followed by protease treatment targeted to enzymatic hydrolysis of wool scales. Using a two-bath process with 5 g/L sodium bisulfite and 8 U/mL protease of Savinase Ultra 16XL, the treated wool fabric demonstrated low felting shrinkage (4.14 %), acceptable strength loss (6.58 %), and minimal alteration in color depth (color difference value <1.1). The present strategy overcomes the drawbacks of conventional protease treatments, particularly the strength loss and color alteration typically observed in dyed fabrics, providing an eco-friendly way for the commercial application of anti-felting finishing of the dyed wool textiles.