Measuring transverse T-1 relaxation times as a function of concentration provides a determination of the hydrophilic surface, wetted with a suspension, as long as the surface relaxation T-1 is known. Likewise, measuring T-1 over time provides a determination of the surface variations during a slow reaction such as when drilling mud sets, which is simulated by a mixture of bentonite, cement and heavy water. Deuterium resonance measurements have the advantage that the relaxation depends little on the presence of paramagnetic impurities or molecular motion in a confined space, which has been demonstrated using a large stratum shale, montmorillonite. This share has been studied as a function of temperature, which makes it possible to measure the surface relaxation T-1 without modifying the suspension.