This study considers the use of rotational rheometry as a laboratory technique to control the efficiency of different commercial deflocculants on kaolin suspensions. In particular, three commercial Penta Sodium Tripolyphosphates (STPP), which are widely used in the ceramics industry, were tested. In order to characterise the Tripolyphosphate (TPP) salts, chemical and physical analyses were carried out. The aim of this study is to highlight the ability of rheometric techniques to describe the effects of the different additives with fast and easy procedures that can be utilised on industrial or laboratory scale. The rheological measures were performed on kaolin suspensions with different amounts of TPPs salts addition. As a liquid medium, industrial water with calcium and magnesium ions was simulated.