01
Many staple fibers start hydrophobic
Untreated polypropylene sheds water. That is what a leg cuff needs. A polyester blend is specified on its own, and the finish is never assumed from the fiber name.
02
A topsheet needs the opposite
A topsheet must let fluid through quickly. A hydrophilic surfactant finish changes how the surface wets, and strike-through time is the measurement that proves it.
03
Durability is part of the spec
Some finishes wash off with repeated insults; others are designed to last. Storage, lotion, and the number of insults the product must handle all belong in the specification.