Effective removal of scales from wool surface through the combination of thioglycolic acid compounds and proteases for anti-felting finishing

The traditional Chlorination-Hercosett method for wool anti-felting processing generates environmentally harmful organic halogens. Anti-felting of wool with enzymes has attracted the attention of researchers for its environmental benefits. Savinase Ultra 16XL, a protease for shrinkage resistance, is effective at breaking down wool scales but can also degrade the CMC layer within the wool fiber, leading to a significant loss of fiber strength. In this study, inspired by the breaking of the disulfide bond in the perm process, thioglycolic acid compounds, sodium thioglycolate (STG) or glycerol monomercaptoacetate (GMT), was used in combination with proteases for the anti-felting treatment of wool for the first time. Comprehensive SEM, EDS, FT-IR, and Raman analyses of wool fibers before and after treatment with thioglycolic acid compounds and proteases. The disulfide bonds in wool scales can be broken by the reduction of STG or GMT, thus facilitating the subsequent hydrolysis of the scales by proteases. The combination use of 5 g/L thioglycolic acid compounds (STG or GMT) and 6 U/mL protease endowed the wool fabric with promising shrink-resistance properties, achieving a felting shrinkage of less than 4 %. Moreover, the anti-felting processing of dyed wool fabrics using the method outlined in this study exhibited promising results, demonstrating excellent shrink-resistance properties and minimal strength loss without changing the color of the fabrics. This work provides an eco-friendly and efficient method for anti-felting finishing of both pristine and dyed wool fabrics.