A critical (steady state) value of the resistivity of different organic coatings was determined by a combination of optical
shearography and electrochemical impedance spectroscopy (EIS). The behavior of organic coatings, i.e., ACE premiumgray
enamel, white enamel, beige enamel (spray coatings), a yellow acrylic lacquer, and a gold nail polish on a metallic
alloy, i.e., a carbon steel, was investigated over a temperature range of 20-60 °C. The value of the resistivity of coatings
was determined by correlating the in-plan displacement of the coating (by shearography over a temperature range of 20-
60 °C) and the value of the alternating current (A.C) impedance of the coating by EIS in 3% NaCl solution. The
integrity of the coatings with respect to time was assessed by comparison the measured value of resistivity to the critical
(steady state) or asymptotic value of resistivity. In other words, by shearography, measurement of coating properties
could be performed independent of parameters such as UV exposure, humidity, presence of chemical species, and other
parameters which may normally interfere with conventional methods of the assessing of the integrity of coatings.
Therefore, one may measure the resistivity of coatings, regardless of the history of the coating, in order to assess the
integrity of coatings. Also, the obtained shearography data were found to be in a reasonable trend with the data of
electrochemical impedance spectroscopy (EIS) in 3%NaCl solution.