Why Don’t Sheep Shrink In The Rain?

The video explains why wool sweaters shrink in the laundry but sheep wool doesn't shrink in the rain. Wool fibers have scales that create friction, causing them to move in one direction, leading to shrinkage when agitated in water and heat. Sheep wool doesn't shrink because it isn't agitated enough in the rain to activate the ratchet effect.

What is the 'ratchet effect' and how does it contribute to the shrinking of wool?

How does water affect the wool fibers during washing?