ABSTRACT
In this study hydrophobic surfaces with increasing roughness were produced by coating glass slides with an amorphous fluoropolymer (Teflon AF1600) containing 50 |im silica spheres. Advancing and receding contact angles were measured by the conventional Wilhelmy plate technique. The contact angle hysteresis was small but significant. By subjecting the system to acoustic vibrations the hysteresis was effectively eliminated. The vibrated contact angle follows the Wenzel equation. The contact angle obtained by averaging the cosines of the advancing and receding angles is a good approximation for the vibrated one provided that surface roughness is rather small.
