Abstract
When the rate of uptake of C. I. Acid Blue 138 on wool was held constant by continuously varying the temperature, either a non–ionic or a cationic ethylene oxide condensate effectively promoted level uptake of dye. Equilibrium sorption isotherms of the dye on wool in the presence of the cationic condensate showed a point of inflexion. Improved levelness in exhaustion dyeing was attained by delaying the addition of the cationic condensate until the concentration of dye had fallen to correspond to the point of inflexion in the isotherm.