Interfacial measurement surface roughness

Current theories to explain hysteresis of contact angles are primarily based on the concepts of surface roughness, surface heterogeneity, friction, and adsorption phenomena. Unintentional adsorption, or contamination—the result of inadequate experimental technique—is, however, the most frequent explanation. As all systems involving solids are subject to the reasons indicated above for hysteresis, we chose the system mercury-benzene-water, which should be affected only by adsorption phenomena, controllable under proper experimentation. An additional advantage is the fact that all interfacial tensions involved can be measured. 

Section II.D, each material was finished by several methods, such as lathing and polishing, in order to measure contact angles for various surface roughnesses. The test liquids were water and 15% ethanol solution for the measurement of the contact angle and water, four kinds of ethanol solution of different concentrations, and two kinds of machine oils for the measurement of the liquid-vapor interfacial tension. 

---