Water Repellence

Wool has the unique characteristics of being hydrophilic towards water vapour; but hydrophobic, or water repellent, towards liquid water.

The outer layer of wool has a hydrophonic epicuticle, off which water runs, while water vapour diffuses into the fibre through microscopic pores in the surface. This is because the molecular structure of the epicuticle is smaller than that of liquid but larger than that of water vapour.