Green miles in dyeing technology: metal-rich pumpkin extracts in aid of natural dyes.

To reduce environmental pollution, it is essential to use green processes in dyeing and meet its requirements. Most natural dyes have a low affinity to be used in the dyeing process. To refine this limitation, the mordanting flow is necessary for many dyeing cases. Pumpkin extract as a natural, metal-rich source can be used as a bio-mordant in green dyeing of natural yarns such as wool. Two natural dyes native to Iran, Reseda luteola and madder, were employed in this study. The effectiveness of bio-mordant presence on yarns was evaluated by FTIR-ATR test from mordanted and mordanted-dyed wool samples. The study of K/S (color strength) content of dyed samples showed that increasing the dye concentration increases the amount of K/S. Fastness performance of wool dyed with pumpkin alternated from good to excellent depending on natural dye type and concentration, due to the formation of complex structures.