This study aims to evaluate the dyeing potential of Tagetes erecta L. extract on Eri silk and examine the effectiveness of Emblica officinalis as a plant-based bio-mordant.
Dye extraction was optimized from dried marigold petals by varying material-to-liquor ratio (MLR), temperature and pH. Pre-mordanted Eri silk fabrics were dyed under acidic, neutral and alkaline conditions at controlled temperatures and durations. Color properties were assessed using CIE Lab* and Kubelka–Munk analyses. Dye–fiber interactions and surface morphology were examined using Fourier transform infrared (FTIR) and SEM, while UV–visible spectroscopy was used to evaluate UV absorption behavior.
An MLR of 1:10 and extraction at 75°C for 60 min were identified as optimal for dye extraction. Acidic dye baths combined with bio-mordanting significantly enhanced dye uptake, producing bright yellow shades with the highest K/S values (up to 2.98). Bio-mordanted samples showed improved wash and light fastness (ratings 3–4). FTIR spectra revealed a shift in the amide I band, indicating strengthened hydrogen bonding between dye molecules and silk fibroin. SEM images confirmed uniform pigment deposition, and UV–vis analysis demonstrated enhanced UV absorption in bio-mordanted fibers.
The marigold–bio-mordant system provides a sustainable alternative to synthetic dyes and metal mordants for protein-based textiles, enabling eco-friendly processing and value addition to Eri silk using renewable plant resources.
This work demonstrates the synergistic use of marigold dye and a plant-derived bio-mordant for the first time on protein-based fiber Eri silk to achieve improved color strength, fastness and functional performance, supporting the adoption of natural dyeing systems in sustainable textile production.
