Visual and instrumental assessment of moisture-induced color change in polyester fabrics

This study investigates the impact of varying moisture levels on the perceived color appearance of polyester fabrics through a controlled psychophysical experiment involving human observers and instrumental colorimetric assessments. A total of 27 fabric samples across 9 color families and 3 depths of shade were evaluated under 3 moisture conditions: dry, 20% wet, and 120% wet. Observers performed paired comparisons using the AATCC Gray Scale for Color Change and categorical judgments of lightness, brightness (chroma), and hue shift. A total of 9720 assessments were thus obtained. Intra- and inter-observer consistency was assessed using STRESS indices and Cohen’s or Fleiss’ Kappa coefficients. Results showed that lightness was the most reliably judged perceptual attribute, with high consistency across and within observers, while brightness and hue judgments were more variable. Exploratory analysis revealed that higher moisture contrasts led to stronger perceived color differences, with directional hue shifts typically occurring along the red–blue directions. One-way ANOVA and Tukey HSD tests confirmed statistically significant differences between all moisture level comparisons. Instrumental color differences (ΔE _{0 0} , ΔL, ΔC, ΔH) exhibited moderate correlation with observer ratings ( r = 0.5812), with the highest agreement observed for lightness (70.21%), followed by brightness (38.72%) and hue shift (27.98%). These findings highlight the limitations of relying solely on instrumental data when evaluating color under variable moisture conditions.