The measurement of the penetration time by detecting the resistance change in a piece of filter paper sandwiched between the back of the foil sample and a copper foil, which was conventionally applied in thin foil penetration experiments, was modified. This preliminary study aims to validate the optical detection of the leakage of the electrolyte on the opposite side of very thin foils of AA2024 (30 mu m in thickness) due to the full penetration of intergranular corrosion. Evaluation of the potential of this approach was tested during intergranular corrosion potentiostatic tests in a 0.1M NaCl chloride solution. (C) 2016 The Electrochemical Society. All rights reserved.