Cordierite-based glass ceramics have been prepared by slip casting from slurries with different dispersant concentrations at a given solids loading (60 wt%). The amount of dispersant was found to have great influence on the rheological behavior of the cordierite-glass suspensions. At low dispersant concentrations the Bingham model could be used to describe the flow behavior, which gradually changed to a Newtonian type when the optimal amount of dispersant was added. Further additions of dispersing agent led to a shear-thickening behavior that could be described by the Casson model. A maximum coverage of dispersant on the surfaces of the particles resulted in the optimal dispersant concentration, which yielded a maximum value of the zeta potential, and thus the lowest viscosity values of the suspensions.