Fabric strength loss and change in colour and tone after textile finishng

Strength loss

Strength loss in cotton finished with reactive resins (cross link embitterment) is known phenomenon. Starting with higher strength of the substrate, controlling the level of resin application and catalyst employed, using additives like poly-ethylene emulsion that improve abrasion resistance, tear strength, lubricity, feel etc. need to be borne in mind.

Change of colour on finishing

Change of color after imparting the finish is a common phenomenon.

‘In a chromophoric molecule (dyestuff molecule), when certain substitution takes place or when present in certain solvents, the absorption shifts – either to a longer wave length (bathochromic – red shift) or to a shorter wavelength (hypsochromic – blue shift). This depends on the characteristics of the substituant or the degree of polarity of the solvent. A change in pH also could cause shift in absorption.

Any disturbance to the chromophore configuration or the auxochrome during dyeing / finishing operations would affect – however small or great, the color perceived’.

Some of the finishing agents may act as mild solvents for the dye (however sparingly) and hence shift the wavelength of absorption, even marginally to alter the tonal color perception. The pH also could play subtle role in altering the conjugated double bond hybrid resonance in certain colors, contributing to a change in color perception. Cationic fixing agents generally change the tone of certain colors. Protonation could be one of the reasons. Some of the resin finishes also show change in hue on certain shades.

In the absence of information to the user, on the entire aspects of the chemistry of finishing agents and of the dyestuffs, it is recommended to check the effect of different finishing agents in use and every time a new finishing agent is tried.

The manufacturers of the finishing agents and dyestuffs also should educate users on the possible impact on the color perception after intense trials in their laboratory. However the responsibility lies entirely with the user as mutual interference of different colors besides finishing agents could alter the results. Proper selection of right colors and finishing agents would be the right approach to avoid problems of uncertainty of right shade in the finished goods. .