Color Degradation
Wet treatment of dyed textile materials determines the resistance of the colorant to bleeding and fading during subsequent laundering. A washfastness failure occurs when the chemical bond between the dye molecule and the fiber is severed, causing color to leach into the washing liquid. This migration of pigment reduces the visual appeal of the garment and risks staining adjacent fabrics.
Migration Mechanism
Dye release during washing occurs due to several factors, including insufficient dye fixation, improper after-clearing, or the chemical action of laundry detergents. When unfixed dye remains on the surface of the fiber, the hot water and surfactants in the wash bath dissolve and release it. In cellulose fibers dyed with reactive dyes, inadequate washing-off of hydrolysed dye is the primary cause of this problem.
Testing Standard
Laboratory evaluation follows standardized procedures, such as those established by ISO 105, which subject textile specimens to controlled wash cycles in the presence of multi-fiber strip fabrics. After the test, the changes in color of the specimen and the degree of staining on the adjacent strips are evaluated using grayscale references. This test simulates multiple home launderings in a single accelerated procedure.
Quality Assessment
Bleeding of dye onto white trim represents a major quality defect that leads to product rejection by retail brands. Identifying a washfastness failure during pre-shipment inspection prevents sub-standard garments from reaching the market.
