Functional Performance and Safety Evaluation of Optimized Plant-Based Dye Mixtures for Intense Hair Coloration

This study aimed to develop a sustainable and safe alternative to chemical hair dyes by exploring the functional performance and safety evaluation of herbal mixtures. Natural dyes were extracted from Lawsonia inermis leaves, Clitoria ternatea flowers, and Indigofera tinctoria leaves using an eco-friendly extraction method with deionized water and ultrasonication. The ratios of these natural dyes were optimized using statistical tools, specifically Minitab, to determine the most effective formulation. The safety profiles and dyeing performance of individual dyes and their combinations were evaluated with a focus on color intensity, stability, and resistance to washing and light exposure. The optimal herbal mixture, with a ratio of 2:2:1:1 (L. inermis/C. ternatea/I. tinctoria/water), demonstrated the highest absorbance and lowest lightness, indicating the darkest color profile. When applied for 30 min, this herbal combination yielded a long-lasting and intense dark color. Further testing using the hen’s egg chorioallantoic membrane test confirmed the favorable safety profile, and examination under a scanning electron microscope showed no damage to the hair cuticle, indicating that the herbal formulation is safer than chemical hair dyes. Therefore, this herbal mixture showed promise as an alternative to synthetic dyes, and further formulation development was suggested.