Study the effect of ammonia post-treatment on color characteristics of annatto-dyed textile substrate using reflectance spectrophotometery

- Bixa orellana is an abundantly growing prominent dye plant.
- B. orellana was tested for dyeing properties on wool fiber.
- Effect of ammonia concentration on color parameters and fastness properties was investigated.
- Ammonia post treatment improved color strength and depth of shades.

This research is aimed to study the influence of ammonia after-treatment on color behavior in wool yarns dyed with annatto extract. The dyeing was carried out using 15% (o. w. f.) dye concentration in presence of stannous chloride as a mordant and then treated with different percentages of ammonia solution. At the same time, color strength, CIE-Lab values and fastness properties of all dyed woolen yarns were also assessed. It was concluded that, in all cases after treatment with ammonia caused a decrease in lightness (L*) values, there was less lightness in the red hue of the wool yarns with the increase of ammonia percentage in solution. The K/S value of annatto dyed wool was found to increase after treated with ammonia. In addition, it was also observed that dyed wool yarns after post-treatment with ammonia did not return to their original color on acidification.