Comparison of Aluminum Mordants on the Colorfastness of Natural Dyes on Cotton

Two mordanting agents, aluminum potassium sulfate and aluminum acetate, in three concentrations (5%, 10%, and 20% owf) were evaluated for colorfastness to laundering and light of natural dye extracts (madder, weld, and coreopsis) on cotton print cloth. The type of aluminum mordant had a greater influence on colorfastness to laundering, whereas dye type had a greater influence on fastness to light. Aluminum acetate at 5% owf concentration gave slightly higher Gray Scale ratings for colorfastness to laundering of coreopsis and weld. All treatments had negligible to no staining on cotton. Weld had slightly better colorfastness to light ratings than the other dye types with 20% aluminum potassium sulfate rating highest. Even though the aluminum acetate mordant improved the colorfastness to laundering on weld and coreopsis at the 5% and 10% owf concentrations, it did not improve fastness to light and resulted in slightly lower fastness to light grades on coreopsis.