Effect of Dye Solution Ionic Strength on Dyeing of Cotton with Reactive Dyes

The controlling effect for dye exhaustion (adsorption) and diffusion (absorption) in a reactive dyeing of cotton is shown to be exerted by ionic strength in the dye solution rather than concentration of inorganic salts used as electrolytes. The study showed that the conclusion applies to both exhaust dyeing for dye exhaustion and pad dyeings for dye diffusion. Further, the addition of an alkali, even though it is not used as an electrolyte, increased the extent of exhaustion (in exhaust dyeing) and diffusion (in pad dyeing) due to increase in ionic strength of the dye solution. Hence, the total ionic strength of reactive dye solution for dye exhaustion and diffusion must be taken into account in order to ensure optimum reproducibility. Means for determining the total ionic strength of exhaust or pad dye solutions for different electrolytes are given.