Raw materials mixtures formed from calcined alumina and zircon (ZrSiO₄), in closed mixing proportions, were prepared as aqueous suspensions, with a view to shaping ceramic products, through pouring in plaster moulds. The maintaining in suspension of mineral particles, 100% nonclay (unplastic), was realised with Arabic gum (A.G.), sodium carboxymethylcelullose (Na-CMC) and polyvinyl alcohol (PVA). The homogeneous-grinding time was maintained constant (5 hours), changing total quantity of additives and their quality. Their influence can be observed both in the grain size distributions of prepared masses and in properties such as: viscosity, pH. Using proof samples sintered at 1300 ⁰C for 2 hours, microstructural investigations were made by scanning electron microscopy. The proof samples present an inhomogeneous microstructure in terms of the size and shape of particles and pores, different for each sample.