Eco-friendly dyeing and finishing of cotton and recycled polyamide 6,6 for increased UV protection and lightfastness

Purpose This study targets the inherent limitations of natural dyes, particularly poor light fastness, by investigating a sustainable sodium alginate/TiO2 finishing approach to enhance UV protection and lightfastness in madder-dyed (Rubia tinctorum L.) recycled polyamide 6,6 and organic cotton fabrics. Design/methodology/approach The finishing process was developed using pad-batch and exhaust procedures, with parameters varying with the TiO2/C6H7NaO6 concentration ratio. The dyed fabrics underwent extensive characterisation using FTIR, SEM, HPLC, and CIELab analyses. Specific color fastness properties, such as washing, rubbing, and light fastness, were explored, and the effect of a finishing on UV-protection capacity was assessed. Findings Fabrics that underwent a finishing process revealed that the alginate-based coating improves dye fixation and fastness by forming a continuous surface film. As TiO2 provides effective UV shielding via scattering and absorption mechanisms, resulting in a substantial reduction in UV-A and UV-B transmission. Practical implications A sustainable finishing approach that improves light fastness and UV protection in natural-dyed fabrics for durable fashion and ready-to-wear products. Originality/value Improved finishing strategies to increase the lightfastness of natural dyes, which have been used since ancient times and are increasingly preferred for sustainability, are important for industrial applications. Protection against harmful ultraviolet radiation (UVR) is essential, making the development of functional textiles critical for minimizing sun exposure. Since most natural dyes exhibit weak to moderate lightfastness, improving their resistance to light and UV protection is necessary. This study presents an improved finishing strategy that enhances light fastness, overall fastness, and UV protection of naturally dyed fabrics, enabling their use in durable, functional, and aesthetically versatile ready-to-wear fashion applications.