The use of reflectance measurements in the determination of diffusion of reactive dyes into cellulosic fiber

Reactive dye fixation and color yield of a dyed cellulosic fiber significantly depend on the dye diffusion into the fiber polymer system. In case of pad‐dyeing processes, dye diffusion exerts a more significant influence on dye fixation and hence color yield. This article proposes a new method for determining the extent of diffusion of reactive dyes into the fiber in pad dyeings using Kubelka–Munk equation. The K/S values are used as in an equation, %D (extent of dye diffusion) = 100 − [(K/S diffusion index )/ (K/S reference ) × 100]. The article introduces and explains how to determine the new K/S variables used in this equation. The new method is simple, nondestructive, relatively faster, and applicable to industrial dyehouses, and was validated by a microscopic analysis of dyed fiber cross‐section carried out in this work and to the dye manufacturer's recommendations for dyebath‐ingredient concentrations.