<p>Peeling and warping of lacquer films on excavated copper-based lacquerware are caused by the absorption of conservation reagents, which is closely related to the distribution of components within the films. This study investigates the factors influencing component distribution, focusing on thermal polymerization and burial environment. Peeled lacquer film from copper ornaments excavated at the Heijo Palace site was analyzed using microscopic observation, SEM-EDX, FT-IR spectroscopy, and compared with simulated samples. Chemical differences were identified between the external and internal surfaces of the archaeological sample. Thermal polymerization was recognized as a factor influencing component distribution and color tone variation. Further chemical changes occurred due to burial. This study enabled the evaluation of component distribution based on formation factors and offers insights into the degradation of lacquer films buried underground. These findings may contribute to the development of conservation treatments that minimize damage to lacquer while stabilizing the underlying metal.</p>