Optical Properties of Cotton Fabrics Dyed with Sappanwood Extracts

This dataset supports the study of sustainable textile coloration using natural dyes by investigating the influence of dyeing conditions on the optical properties of cotton fabrics dyed with sappanwood (Caesalpinia sappan L.) extract. The dataset includes systematic experimental results examining the effects of solution pH and oxidation–reduction potential (ORP), mordant type and concentration, mordanting sequence, dye concentration, dyeing temperature, exhaustion time, and washing durability on dye performance. Optical characterization data comprise reflectance-based colorimetric parameters as well as UV–Vis absorbance and transmittance spectra over a broad wavelength range. The dataset demonstrates that dyeing conditions strongly affect color development and optical behavior, with pH identified as the most influential parameter and optimal color strength obtained at pH 6.0. Spectral analyses indicate that pH mainly influences absorption intensity rather than spectral peak position, suggesting that dye uptake and fixation are more significant than chromophore structural changes. The dataset also shows that iron- and copper-based mordants modify fabric shade and enhance light absorption, while moderate dyeing temperatures and approximately 60 minutes of exhaustion time are sufficient for effective coloration. Washing durability data reveal increases in lightness (L*) and color difference (ΔE) after repeated laundering, although the dyed fabrics maintain strong ultraviolet-blocking capability characterized by low UV transmittance.