Non Fluorinated Durable Water Repellent Wet Processing Specifications
Non-fluorinated DWR wet processing requires bath pH 4.0-5.5, WPU control, and core cure temperatures of 150-170°C with crosslinkers to pass 10 ppm fluorine limits.
Foulard Padding
Impregnation Process
Mechanical wet processing equipment applies liquid finishes, dyes, or functional chemicals to continuous fabric lengths by immersion and subsequent compression. Industrial finishing mills use foulard padding to ensure that liquid treatments penetrate deeply into the yarn structure rather than sitting loosely on the fabric surface. This processing method guarantees a uniform distribution of chemicals across both the warp and weft directions.
Squeeze Mechanism
Dual rollers constructed of steel and hard rubber compress the wet fabric under high pneumatic pressure to expel excess liquid. Adjusting the nip pressure of these rollers determines the wet pickup percentage, which controls the precise amount of chemical left on the textile before drying. Modern foulard padding machines feature variable-profile rollers to prevent uneven chemical distribution across the width of the fabric, ensuring that the selvages and the centre receive equal pressure.
This mechanical adjustment is indispensable to avoid dry spots or wet edges that would ruin subsequent curing stages in the stenter frame.
Absorption Dynamic
Fibres must remain in the chemical bath long enough to achieve complete wetting and displacement of trapped air. Because foulard padding relies on rapid compression and recovery, yarn twist and weave density directly influence the efficiency of the chemical uptake. Densely woven fabrics require longer dwell times or surfactant additives to achieve uniform wet pickup.
Industrial Verification
Production managers verify the wet pickup rate by weighing a fabric sample before and after the compression step. Consistent foulard padding prevents common defects such as shade variation, chemical migration during drying, and uneven softness across the garment production lot. Laboratory trials simulate these industrial squeeze pressures to match finish recipes to bulk production runs.