Determining Raw Cashmere Micron Profiles and Dehairing Yields
Determining raw cashmere value requires combined OFDA micron profiling and oven-dry yield mass balance testing to calculate true clean dehaired cost.
Directional Friction
Surface Resistance
An asymmetrical surface resistance occurs when a fiber displays a different coefficient of friction when rubbed in opposite directions. This directional friction is most pronounced in animal fibers like wool, where the surface scales point in one direction. The difference in resistance determines how fibers move against each other during washing and spinning.
Fibrous Structure
Serrated scale structures on wool fibers act as microscopic barbs that slide easily in the root-to-tip direction but lock when pulled tip-to-root. This unique behavior causes the fibers to migrate and lock together, a mechanism that drives the felting process. Other natural or synthetic fibers with smooth surfaces do not show this directional variation.
Processing Effect
Washing wool fabrics without chemical treatment causes them to shrink and consolidate as fibers lock irreversibly due to their mechanical behavior. Finishing processes often apply softeners or polymers to mask these scales and reduce the directional resistance. Minimizing this effect prevents undesired shrinkage and maintains fabric soft hand over multiple wash cycles.
Functional Measurement
Testing instruments measure the force required to pull a fiber or yarn across a standard friction surface in both directions. The resulting ratio is known as the friction coefficient difference, which laboratory technicians use to evaluate the effectiveness of anti-felting treatments. Consistent testing helps mills guarantee that machine-washable wool garments will not shrink during home laundering, avoiding commercial disputes over damaged shipments.