Wool retains its wicking ability even after it is spun into yarns then woven into pads, wraps, blankets and coolers. All those little air pockets also explain a woolen paradox. Wool provides warmth because those air pockets insulate. But those pockets also allow air to circulate freely, dispersing excess heat rather than holding it against the skin. Here is where those fears of washing come in.
Riders are afraid to wash woven or knit wool fabrics because of shrinkage.
They are afraid to wash sheepskin because of its marriage of leather and wool. Sheep don't shrink in the rain because water alone does not shrink wool. It is a combination of hot water and agitation that does the deed. In fact, manufacturers produce wool felt by agitating thick layers of wool fibers in hot water until they shorten and lock tightly together. So riders should not be afraid to wash wool as long as they use the right techniques.