Root Cause Analysis of Color Migration in Footwear A Case Study

Abstract

The phenomena of migration and/or bleeding of colorants are one of the major concerns for the footwear and leather goods industries. The migration/bleeding of the colorants from one component to the other has been observed in many cases that spoil the aesthetics of the product, which in turn leads to economic loss for the industries. In this research article, a typical case of color migration in leather footwear has been studied in depth for root-cause analysis of the migration problem. The leather used in the shoe upper (affected due to migration), the lining fabric, and the adhesive used in making the footwear were characterized by microscopic and spectroscopic techniques. The FTIR-ATR study revealed that the leather was finished with polyurethane-based coating, the lining fabric used was an aromatic polyester and the adhesive was natural rubber-based adhesive. Though the lining fabric was colorfast to rubbing, it released color in all the organic solvents generally used in natural rubber-based adhesive. Migration studies showed that migration of the colorant (black) from the lining material to the leather (white) happened only in the presence of the adhesive. In conclusion, the organic solvent present in the adhesive used in making the footwear was responsible for the color migration from the lining material to the attached leather. Finally, recommendations have also been made to avoid such problems of color migration in products made from a variety of multiple fabrics.