This study examines the aging behavior of mastic samples subjected to hygrothermal condi-tions in a pressure aging vessel (PAV) for 10, 20, and 40 hours, as well as to reactive oxygen species and hu-midity in Vienna Binder Aging (VBA-WET). Fourier-transform infrared spectroscopy (FTIR) was used to analyze the chemical aging processes, and principal component analysis (PCA) was applied to differentiate mastic types and evaluate the efficacy of indices versus spectral data. Results show that W60k mastic has lower carbonyl index and smaller increase of sulfoxide index, indicating greater resistance to oxidative degra-dation compared to W mastic. PCA effectively differentiates the mastic types and confirms that both FTIR indices and full spectra distinguish between mastic types. These findings highlight the impact of filler compo-sition on aging behavior and suggest directions for future research on material performance in practical appli-cations.