Color Movement
Uncontrolled movement of dyestuffs within or on a wet textile substrate during drying results in shade variation across the fabric width or thickness. This dye migration occurs when liquid water carries dissolved dye molecules toward the hot evaporation surface. It produces a concentrated layer of color on the exterior of the yarn or fabric while leaving the interior pale.
This defect compromises the color fastness and appearance of the finished product.
Thermal Influence
Capillary action draws water from the cooler, wetter interior toward the outer surface where evaporation is active. Since the dyestuffs are dissolved or suspended in this water, they travel with the liquid phase until they reach the evaporation boundary. If the drying rate is high and unbalanced, dye migration occurs more rapidly and creates a pronounced difference in color between the face and back of the fabric.
Process Control
Minimizing this phenomenon requires the use of anti-migration agents in the pad bath and controlled pre-heating. Infrared pre-dryers raise the fabric temperature without causing air movement, which reduces capillary flow before the fabric enters the hot-air stenter. Keeping the moisture level below thirty percent before stenter drying begins stabilizes the dye distribution.
Product Fault
Visual and instrumental assessments of the fabric face and back confirm whether the dye has remained in place.
