Effect of corona discharge treatment on indigo dyed cotton fabric

The present study proposes new conditions for achieving the aged‐look effect of denim. Indigo dyed cotton fabrics were treated by corona discharge at different power levels and number of passages. Colorimetric parameters of corona treatment were assessed by the CIE L*a*b* colorimetric system and the pH and colour fastness of samples were tested. The surfaces of dyed samples were studied by scanning electron microscopy and Fourier Transform–infrared/attenuated total reflectance (FTIR/ATR) analysis. Under the same conditions of corona treatment, the faded‐look effect was reduced as the depth of dyeing was increased. Increasing the power and the number of passages increases L* and b* and decreases a* values. This indicates that samples become lighter and yellower but soaping can reduce yellowness. FTIR/ATR results show that indigo dye oxidises, and isatin and anthranilic acid are produced. The pH levels of corona‐treated samples reduce as the power and number of passages increase. This acidification is in agreement with the results of FTIR/ATR analysis.