The ability of the wet jet milling method to pulverize nanosized alumina suspensions for sheet casting has been discussed from the point of view of particle-particle separation distance in the slurry. The amounts of polymer additives were optimized to give a stable, ready-to-cast slurry based on rheological measurements. Assuming that the polymers take on a sandwich configuration between particles poly (acrylic acid)/polyvinyl alcohol (surface/PAA/PVA/PAA/surface layers), then 9.1 nm, the calculated surface-to-surface separation distance (SSD) between particles could be taken as the criterion to prepare crack-free sheets. Indeed, the sheets prepared from the slurries, satisfying the above condition, were crack free. However, for the slurries with less space between particles, due to the inability of PVA to bind them all, cracks were formed in the cast sheets. The agglomerated particles in the slurries also influenced the macroscopic behavior of the sheets. Therefore, a well-dispersed slurry with a large enough SSD is necessary for the preparation of crack-free ceramic sheets from nanosized particles.