Receding angle

The receding angle is the contact angle between a liquid and a solid which has already been wetted with the liquid and which is in the course of being de-wetted. Like the advancing angle, the receding angle is a dynamic contact angle.

Background

The receding angle is usually smaller than the advancing angle. The difference between advancing angle and receding angle is referred to as hysteresis. It is a measure of the roughness of the solid surface.

Measuring methods

• Reduction in the volume of an already positioned sessile drop in drop shape analysis. The volume of the drop is reduced manually or with a motorised piston. At the same time, images are recorded and evaluated.

• Measurement of the Wilhelmy contact angle by measuring the force on a vertically suspended plate which is immersed and withdrawn during the measurement. The receding angle is the result of the measurement when withdrawing the plate.