The interaction of a dilute aqueous dispersion of alumina grains (150 nm in size) with a mica substrate has been studied with an atomic force microscope. Atomic force microscopy was used to characterize the structure of the adsorbed layer. The work is focused on the reversibility with time of the deposition process; this is checked by aging a preadsorbed layer in a particle-free aqueous solution. Three types of behavior have been observed, depending on the composition of the aging solution. On one hand, when the preadsorbed layer is aged in pure water or in a solution of passive salt (NaNO3), it remains unaltered with time. On the other hand, when a low concentration of citrate (less than 5mM) is present in a solution at pH greater than 5, the structure of the layer is drastically altered with time: the particles slowly migrate along the surface to form two-dimensional clusters. The last situation is obtained when the concentration of citrate is too high (>5 mM), yielding a total desorption of the layer. Direct force measurements between an alumina grain and mica have further shown that the role of citrate is double: it reverses the sign of the charge on the alumina grain and it also decreases (but not cancels) the adhesion between the grain and the mica substrate.