Additive effects on cotton dyeing with dye extract from achiote seeds

Abstract

Cotton yarns have been pretreated with the additives, such as chitosan, microcrystalline chitosan, quaternized chitosan & aqueous extract from the fruit of <em>Diospyros mollis</em> Griff, as well as with the commercial formaldehyde-free cationic fixing agent (Sera^® Fast C-NC) & alum (post-mordanting), and their dyeing fastness properties are studied. These treated cotton yarns are then dyed with the annatto dye extract from <em>Bixa orellana</em> L. (Achiote) seeds and tested for different properties including <em>K/S</em> value, light fastness, and wash fastness. Pre-treatment of cotton yarn with chitosan or microcrystalline chitosan solution (together with glyoxal cross-linking) or quaternized chitosan, or Sera^® Fast C-NC before dyeing, shows a better color depth (<em>K/S</em>) and improved wash fastness properties in comparison to yarn with alum post-mordanting and the untreated cotton yarn. Improved light fastness is also obtained on inclusion of the anti-oxidant ascorbic acid in the post-treatment protocol. These additive treatments thus offer considerable potential for the improved annatto dyeing of cotton.