Exposure Duration
Immersion duration of a textile web in a liquid treatment bath governs the amount of chemical or dye absorbed by the fibers before the fabric is squeezed by the padder rollers. An optimal pad trough dwell time is necessary to allow the wetting agents to displace the air trapped within the yarn structure. If this duration is too short, the dye liquor only penetrates the surface fibers, resulting in poor rub fastness and internal pale areas.
This variable must be carefully matched to the fabric thickness and processing speed.
Hydrodynamic Factors
Fabric speed and the length of the immersion path through the padder trough determine this time. When the range runs at higher speeds, the path must be extended by using a deeper trough or additional guide rollers to maintain the target exposure. Roller adjustments are necessary to ensure that thick cotton fabrics receive adequate liquor exposure.
Absorption Efficiency
Short exposure leads to uneven penetration in heavy fabrics such as denim or twill. To prevent this, chemical wetting agents are added to accelerate the liquid penetration when speeds are high.
Process Parameter
Production logs record this setting for each fabric qualities to ensure repeatability between different batches.
