In this work suspensions containing natural amorphous silica fibers (NASF), amorphous silica gel and nanometric colloidal amorphous silica were prepared and rheologically analyzed. The suspensions were prepared by varying the volume percentage of solids between 22 and 32%, ammonium polyacrylate (APA), as dispersant, from 0 to 5% and polyvinyl alcohol (PVA), as binder, between 1 and 3.5%. The mixtures were obtained in a propeller mechanical mixer and formed by slip casting. The results of rheological characterization indicated that the suspensions with 30% solids, 4% dispersant and 3% binder were those that showed a stable rheological system and suitable for processing by slip casting.