Glazed ceramic tiles are used for wall and floor covering thanks to their high resistance to chemicals attacks, although big efforts should be done to increase their surfaces resistance to mechanical stresses. This study investigates the applicability of a well-known glass hardening process to glazed ceramic tiles following a rational design based on Design of Experiments technique. A Mixture Design has been carried out to formulate new frits compositions to enhance the ion-exchange process, starting from a commercial product. Vickers Hardness and SEM-EDS techniques have been employed to evaluate the frits and elaborate the model. Results suggest that frits for ceramic tiles are positively affected by ion-exchange process only if an appropriate combination of ions in the starting composition is present, establishing a new category of frit formulations suitable for that purpose. The results have been confirmed employing the optimized frit for the glazing of porcelain stoneware.