This paper investigates the impact of marker pens on the final performance of tank linings when used during the inspection process. The study focuses on chemical resistance and intercoat/substrate adhesion, employing a range of different marker pens and evaluating their compatibility with various epoxy tank lining systems. Five different coating systems and three different marker pen brands were tested, and the results revealed a significant disparity in performance. Surprisingly, only one of the tested marker pen brands demonstrated zero failures in terms of both chemical resistance and intercoat/substrate adhesion, for the five tested coating systems. These findings underscore the critical role that marker pen selection plays in maintaining the integrity and longevity of tank linings. The study provides valuable insights for industry professionals, aiding them in making informed decisions when choosing marker pens for inspection purposes, enhancing the overall performance and durability of tank linings.