Effect of Urea on Dyeing of Wool with Madder

The influence of urea as an additive in dyeing of wool with madder was evaluated in this work. A different concentration of urea was applied on wool yarns before, during and after dyeing of samples. The treated samples were tested for dye absorption at different time, wicking, sinking, wash and light fastness and surface morphology by scanning electronic microscope. The results show that urea is an effective additive in dyeing of wool by madder by increasing the dye absorption. Adding of urea ranging 50% to 250% on weight of fibers leads to swell the wool fibers however, increasing the urea percent to 300% may damage the fiber surfaces and reduces the fiber strength.