The Wilhelmy method, a critical and practical review

A brief history of the Wilhelmy technique for surface tension and contact angle measurements introduces the equation and the methods necessary to correctly apply this modern and automatic procedure. Many simple practices may avoid systematic errors and allow reliable results to be obtained for both quantities. The paper analyses simple runs, i.e. the application to standard shapes as cylinders and parallallelepipeds, but also non-simple runs, i.e. to non- standard samples such as disk-shaped, to porous and flexible samples, to more viscous fluids, etc. Many experimental details such as the size ratio of specimens to the liquid container may be extremely important; their role and the history of discussion about those topics are reviewed and discussed herein.