Acrylic yarns pre-treated with different mordants and their dyeing potential with annatto dye

Abstract

The study aimed to identify the best conditions for dyeing acrylic fiber with natural annatto dye, considering the presence of metallic mordants such as alum and ferrous sulfate, and evaluating the influence of soy milk or the absence of a mordant. Exhaust dyeing tests were conducted with the extract at different pH ranges to understand the behavior of the carotenoids bixin and norbixin in annatto seeds. Color intensity was measured by spectrophotometry, while colorfastness tests were performed to assess color transfer. The alum mordant showed less colorfastness than dyeing without a mordant, suggesting interference in dye fixation despite high color intensity values. On the other hand, the ferrous sulfate mordant exhibited limited leveling but high colorfastness. The natural pH range of the extract with soy milk mordant demonstrated good colorfastness and moderate intensity, resulting in a light-yellow shade. These findings underscore the complexity of interactions between natural dyes, synthetic fibers, and different mordants, emphasizing the importance of considering various factors to optimize desired outcomes in acrylic fiber dyeing.