ABSTRACT
The sessile droplet or sessile bubble contact angle is measured in the static mode, i.e., the droplet or bubble remains on the surface stationary. The advancing contact angle is measured by advancing the three-phase line by increasing the volume of a sessile droplet or bubble, but the measurement is done with a stationary sessile droplet. Depending on whether the contact angle is measured in the process of increasing or decreasing the volume of droplet, the contact angle is referred to as advancing or receding, respectively. The contact angle measured by ‘‘advancing’’ contact angle or ‘‘receding’’ contact angle is not the dynamic contact angle that is observed with a moving three-phase line.
