In colloidal isopressing, a preconsolidated slurry with a high relative density (similar to0.58) is converted into an elastic body (compact) under the influence of an isostatic pressure. Experiments suggest that during isopressing, the preconsolidated slurry is separated from the elastic body by a transition plane that rapidly moves into the preconsolidated slurry, leaving behind the elastic body which is formed against a piece of porous material present within the rubber mold. The porous material will accommodate the liquid phase squeezed out of the preconsolidated slurry, allowing for the conversion to the denser elastic body (similar to0.63). The results of experiments with varied isopressure are compared with simulations based on a filtration model. The good agreement indicates that colloidal isopressing can be considered a special case of consolidation via pressure filtration. Compared with conventional pressure filtration, the extremely rapid consolidation is due to the high relative density of the preconsolidated slurry used to fill the mold as well as the high applied isopressure. The simulation used here is a useful tool in the design and understanding of shape forming by colloidal isopressing and shows how process variables such as particle size. relative density, and applied pressure influence compact formation time.