Experimental and Statistical Examination of the Use of Acids and Mordants in Wool Dyeing with Cochineal Natural Dye

Abstract

The use of natural dyes in textile dyeing supports sustainable textile production by reducing reliance on synthetic dyes, which are highly detrimental to the environment. Replacing traditional mordants, used to enhance properties like fastness, with eco-friendly alternatives further promotes green production. This study examines the dyeing behavior of wool with cochineal natural dye in the presence of organic and metal mordants. The results were analyzed in terms of colorimetry, fastness, antioxidant, and ultraviolet (UV) protection properties. Variations in color coordinates caused by different mordants were evident in the color shades. Organic acid mordants increased the yellowness and redness of the color, while iron and copper mordants shifted the cochineal tone slightly toward bluish hues, whereas aluminum mordanted samples showed a shift toward yellowish tones. Natural mordants enhanced color strength, particularly when applied after the Fe metal mordant. Comprehensive color fastness assessments demonstrated good washing and light fastness with cochineal-dyed wool using copper–iron/organic mordant combinations. Wool yarns dyed with cochineal exhibited improved antioxidant and UV protection properties, which were further enhanced with mordants. Although natural mordants emerged as viable alternatives to metal mordants, combining them with metal mordants yielded superior results in terms of colorimetry. Additionally, regression analysis was conducted on the experimental results to predict color strength relative to wavelengths for specific mordant combinations. Nonlinear regression models—specifically second-, third-, and fourth-order polynomials—successfully predicted color strengths for given mordant treatments, showcasing the potential of such models to estimate results without conducting experiments. In conclusion, dyeing wool with natural dyes in combination with metal-natural mordants demonstrated promising outcomes.