Absorbency Evaluation
Standard testing of bleached or finished fabrics ensures they can quickly take up liquid during subsequent dyeing and finishing processes. This laboratory method, designated aatcc 79, measures the time in seconds required for a single drop of water to be absorbed by a textile specimen. The evaluation establishes whether prepress preparations have successfully removed natural waxes and pectin from the cotton fibers.
It applies to woven and knitted goods before they enter the dye pad.
Standard Procedure
A conditioned fabric sample is mounted flat without tension beneath a burette that dispenses a single droplet of distilled water from a set height of nine millimeters. Once the droplet touches the textile, a timer is started and then stopped the instant the reflective liquid surface disappears from the fabric. Wetting times of less than five seconds indicate thorough preparation and high absorbency.
Longer times reveal that residual hydrophobic waxes remain on the fibers.
Moisture Assessment
Testing is conducted in a controlled atmosphere of sixty-five percent relative humidity and twenty-one degrees Celsius to prevent ambient moisture variations from skewing the results. Unconditioned fabrics can yield false positives if they are overly dry. The test cannot distinguish between the presence of synthetic wetting agents and the true removal of natural cotton waxes.
Acceptance Boundary
A textile lot must achieve a uniform absorbency across the entire fabric width to prevent shade variation during continuous dyeing. When absorption times exceed five seconds, the batch must undergo further scouring.
