A model of the transfer of water from an initially uniform wet slurry to a dry material is described and tested. The model requires that the hydraulic conductivity and water potential of the two materials be well-defined functions of the water content. It permits the prediction of the time course of the redistribution process and the evolution of the water content profiles in each material. It offers an explanation of aspects of the capillary suction time method used to estimate the "filtrability" of slurries, and of slip-casting, and in particular offers a physically based method for optimising that process.