After a two-year intensive university-level preparation in Maths, Chemistry and Physics, Anaëlle joined Chimie ParisTech, a member of the PSL University, in 2022. Today, she continues her studies in chemical engineering at this prestigious institution, specializing in industrial processes and cosmetology. During her internship at the NOVA School of Science and Technology, within the VICARTE department, Anaëlle became passionate about studying the degradation of eosin lake pigments. She conducted photochemical experiments (irradiation experiments) with eosin lake pigments prepared according to historical recipes to study their photostability. The study of mechanisms occurring after light absorption is complex and poses a major challenge in heterogeneous systems such as those found in works of art. The eosin paints of hand-painted glass lantern slides were analyzed using various physicochemical techniques. These results were compared to those obtained for prepared pigments and irradiated samples. Through the physicochemical characterization of artificially aged samples, Anaëlle has risen to the fascinating challenge of identifying the key factors and mechanisms promoting degradation in order to ultimately prevent it.