Crape myrtle flower extract as a plant-based dye for silk: Performance and mordant optimization

The growing demand for sustainable textile colouration has shifted attention towards natural dyes. This study assesses crape myrtle (Lagerstroemia indica) flower extract as a plant-based dye for silk fabrics. Pre-, meta-, and post-mordantation were performed with aluminium, copper, and ferrous salts. Color strength (K/S) and fastness properties were assessed in accordance with ISO standards. The highest color intensity (K/S: 4.56) and superior overall color fastness were found with pre-mordantation with aluminium salt. Perspiration fastness ranged from 3 to 4 for all samples. At the same time, lightfastness and rubbing fastness were highest for aluminium and copper salts (4–5), with ferrous salt giving lower performance (3–4). Washing fastness was also highest in silk samples mordanted with aluminium and copper salts. FTIR analysis confirmed that the silk fibers maintained their structure in all dyeing processes. These results show that pre-mordantation with aluminium salt enhance dye uptake and fastness. Overall, the result highlights crape myrtle extract as a viable, eco-friendly natural colorant for high-performance silk fabric dyeing.