It is well known that the pack tests normally used to evaluate the corrosion resistance of tinplate in the can industry are inadequate for routine work. In this paper, electrochemical impedance is presented as an alternative. Using this technique, it was possible to characterize the better lacquer between two "first line" products. Variables involved in the lacquering, such as dumber of coats and curing temperature, were taken into account. Variables involved in the packing process, such as sterilization and mechanical deformation, were also studied. The general results pointed out that impedance is a powerful tool, giving meaningful and non-subjective information about the quality of the lacquered tinplates in a short time.