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 Diospyros mollis Griff, as well as with the commercial formaldehyde-free cationic fixingagent (Sera® Fast C-NC) & alum (post-mordanting), and their dyeing fastness properties are studied. These treated cottonyarns are then dyed with the annatto dye extract from Bixa orellana L. (Achiote) seeds and tested for different propertiesincluding K/S value, light fastness, and wash fastness. Pre-treatment of cotton yarn with chitosan or microcrystallinechitosan solution (together with glyoxal cross-linking) or quaternized chitosan, or Sera® Fast C-NC before dyeing, shows abetter color depth (K/S) and improved wash fastness properties in comparison to yarn with alum post-mordanting and theuntreated cotton yarn. Improved light fastness is also obtained on inclusion of the anti-oxidant ascorbic acid in the posttreatmentprotocol. These additive treatments thus offer considerable potential for the improved annatto dyeing of cotton.