Continuous Pad Dyeing Shade Drift Control across Variable Humidity Wet Processing Routes
Dynamic control of ambient regain, pad bowl deflection, wet-bulb drying temperatures, and steam saturation halts continuous shade drift across variable weather.
Edge-Center-Edge Shading
Shade Variation
Transverse color variation across the usable width of a processed fabric roll results in mismatched panels during garment assembly. This edge-center-edge shading occurs when the dye pickup or thermal fixation is non-uniform between the edges of the fabric and its center. It appears as a gradual change in color depth or hue from one selvage to the other.
This defect causes fabric wastage because adjacent panels must be matched perfectly.
Mechanical Cause
Incorrect pressure distribution across the padder rollers is the primary cause of this phenomenon. If the rollers are worn or improperly crowned, they exert more force at the edges than in the middle, leaving more dye liquor in the center of the fabric. Additionally, uneven heating in the stenter or pre-dryer can cause more rapid drying at the fabric edges, drawing more dye toward them.
Diagnostic Method
Colorists detect this pattern of variation by taking spectrophotometric measurements across the left, center and right sections of the roll. They calculate the color difference between these points to map the profile of the deviation.
Process Rectification
Adjusting the squeeze roller pressure or calibrating the heater nozzles across the stenter width corrects the underlying thermal or mechanical imbalance.