New varistors compositions are often directly evaluated in relation to varistor electrical characteristics. The compositions are well known since it is easy to weigh with accuracy the single oxides raw materials. However, this paper emphasizes the fact that the compositions of ceramics used to carry out electrical measurements differ from green ceramics. For instance and depending on the conditions, it is shown that bismuth can be either vaporized or can diffuse inside the substrate during the sintering. To reduce the loss of material we suggested using a new route where ceramics are produced by mixture from pre-synthesized spinel and pyrochlore phases with the other classical single oxides additives such as Co, Mn, Cr, Ni, etc.