Organic coated metals are often exposed to accelerated laboratory tests to determine coating protectiveness and ultimately to predict lifetimes. However, discrepancies with field exposures are sometimes observed. Ultimately, we would like to develop an accelerated laboratory test that can reliably predict coating lifetime using a known acceleration factor. In this work, effects of UV, O3, and RH are studied using PVB coatings on 1018 steel as a model system. The primer/substrate interface degradation is analyzed by measuring cathodic delamination with a Scanning Kelvin Probe (SKP) and IR spectroscopy. Exposure to UV, O3, and RH was performed for 4 days in a weathering chamber and the cathodic delamination rate was then measured in the SKP chamber during exposure to lab air with 95% RH. Cathodic delamination was accelerated when the sample was first degraded in the weathering chamber or during exposure in coastal environment.