In the present study, a zirconia -based primary slurry free from silica (S-0) was prepared by replacing the colloidal silica sol binder in the commercial zirconia-based slurry (S-6.4) with an aqueous-Polymer binder. The results of XRD, SEM, and Line Scan analyses from the surface of cast samples show that the thickness of reaction layer has been decreased from 10µm to 6µm in the samples S-6.4 and S-0, respectively. Also, the microhardness tests obtained from the sample surfaces show a 80µm decrease in the surface-hardened layer.