Colorimetric Properties of Wool Dyed with Cochineal: Effect of Dye-Bath pH

I n the present work an evaluation was carried out on the effect of dye-bath pH and mordant type on the obtained shades and fastness properties in wool dyeing with cochineal. In this way wool samples were first mordanted with four different mordants and subsequently dyed with cochineal at different dye-bath pH values of 1 to 9. Colorimetric evaluations were carried out and the fastness properties of the dyed samples were assessed. Changes in the chemical structure of the dye in different pH conditions were also discussed. It was found that the pH of the dye-bath has a great effect on the obtained shades. Based on the results, a combination of dyeing in different values of dye-bath pH from 1 to 9 along with mordanting with various mordants can considerably develop a range of obtainable hues in dyeing of wool with cochineal. Based on the obtained results, the studied different pH conditions have not significant effect on the fastness properties.