encapman said:
Keep in mind what a fluoro-chemical does. Its role is to lower surface tension. That's basically a fluoro-chemical's entire function. That is why an egg easily slides from a non-stick pan - because the surface tension of the pan is lower than the surface tension of the egg. And lowering the surface tension of carpet fiber isn't something that will easily vacuum away.
Here's what lowering the surface tension of the fiber will accomplish: By lowering the surface tension the wetting action of the detergent will increase. It helps the encapsulated soil to vacuum away from the fiber. It will also help retard the wicking process. And it adds soil-resistance to the carpet.
I would hate to see people confused by proper use of terms when they take a
CCT or read the S-100, which is revised for technical correctness. Solids do not possess "
surface tension", per se, as that term is specific only to liquids. What a protector does, upon curing, is lower the
Surface Energy of the fiber below that of the Surface Energy of a potential penetrating liquid. Surfaces are wetted (stained) by liquids that have equal or lower surface tension than the surface energy of a fiber’s surface. People are more familiar with the term "surface tension", so it has a tendency to be used to describe solids for simplicity, which it should not be if we use terms correctly, as is done in the
CCT.
Justine Franchina of DuPont did a fantastic job at contributing to a thorough coverage of protector explanation in the revised standard, which I certainly have not have done justice in the short paraphrased synopsis excerpt.