Electrochemical Impedance Spectroscopy (EIS) is an accepted laboratory technique for evaluating coatings in an electrolyte. Recently, sensors have been developed which allow EIS to be taken on surfaces in any orientation and without foreign electrolyte, consequently allowing a coated metal surface to be measured in-situ. These sensors have been demonstrated in the laboratory to acquire spectra equivalent to the traditional technique, and add the advantage that coatings may be examined while still in test environments such as constant humidity or salt fog. With the addition of a field-ready portable potentiostat, these sensors can become valuable tools for coatings inspection in the field. A sensor may be permanently mounted to a structure, or may be pressed
against a surface only for the duration of a measurement. The sensor results allow ready evaluation of the moisture content of a coating, consequently providing an early warning of impending substrate dam-
age before serious under-coating corrosion has an opportunity to begin.