Feathers, contact angle

Natural superhydrophobic surfaces [1, 2] as observed with leaves of some plants or feathers of some birds, correspond to hydrophobic surfaces whose water contact angle (0) is higher than 150° [3], Such surfaces are sometimes called self-cleaning surfaces since a water droplets will take up the dirt particles and roll off the surface [2], The values of water contact angles cannot be obtained with real surfaces, as... 

---