This paper is concerned with the reproducibility of some parameters ty
pically obtained from impedance diagrams and used for studying the beh
aviour of painted specimens. These parameters are the diameters of hig
h and medium frequency semicircles in a Nyquist impedance plot, the el
ectrical capacitances obtained from the frequency at which the reactiv
e component reaches a maximum in those semicircles, the slope of the l
ow frequency tail, and the impedance modulus at 1 mHz.