Dye Diffusion – The Key to Efficient Coloration

More than any other factor, the rate and degree of diffusion of dyes into the individual fibres composing any textile substrate control the productivity, reproducibility and the quality (with respect to appearance and sometimes the fastness properties) attained in each process. Using direct (fibre cross-section) measurement of the degree of penetration of dyes into nylon, polyester and acrylic fibres, under a variety of application conditions, the relationships between dye penetration and visual colour yield has been determined with fibres differing in cross-sectional shape and delustrant content. The present interest in saving energy, time and water has led to numerous processes resulting in ‘ring-dyeing’. Batchwise dyeing for relatively short times or at somewhat abnormal temperatures, and continuous dyeing by rapid steam-fixation techniques are examples which have been investigated to define application conditions that might be expected to cause problems in bulk-scale production