The contact angles and the hysteresis of organic liquids on the polytetrafluoroethylene surfaces which were prepared by various techniques were measured. The relations of contact angles to hysteresis were then systematized and a method was proposed for estimating the equilibrium contact angle by analyzing the relationships.
When the estimated equilibrium contact angles of several organic liquids were used in the theory for the estimation of solid surface free energy, fairly consistent values of the surface energy of PTFE were obtained.