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Surface properties in terms of surface free energy of solid particles were investigated using capillary rise experimental methods based on Washburn's equation. Two different approaches related to height and weight gain measurements were validated by silica flour and calcium carbonate surface studies. Dispersive components of the surface free energy and nondispersive components of solid–liquid energy of interaction were computed. Some differences observed are related to experimental data acquisitions. Many experimental difficulties, which led in the past to inaccurate wettability characteristics, have been controlled. A new link to the so-called geometrical factor of Washburn's equation has also been established after comparison of theoretical and experimental static and hydrodynamic radii. The high precision of the weight gain approach was achieved by strict control of experimental parameters such as temperature, powder packing, and sintered glass porosity.

The interactions of glass fibers of different compositions with Ca II solutions have been studied using streaming potential techniques. This study clearly showed the formation, on the glass surface, in basic medium, of a layer enriched in Ca(II), giving the glass a better resistance to corrosion in slightly acid medium. This surface layer is characterized by an isoelectric point (IEP) superior to the one of the untreated fiber.

Inverse gas chromatography (IGC), at zero surface coverage, has been used to follow the variation of the surface free energy characteristics of muscovite samples after grinding either in water or in organic media. For initial mica, the value of γ S D measured through IGC, is in agreement with the values given by other methods (30 mJ/m 2 After grinding, γ S D increases and reaches a value of 90 mJ/m 2 when the operation is performed in methanol. At the same time, the acid/base surface properties change as qualitatively indicated by IGC. The variation in surface characteristics, upon grinding, may have significant consequences for the utilization of mica as a filler for composite materials.