Re-conservation of Waterlogged Wooden Oars Excavated from Wolji, Korea: Integrating Archival Research and Technical Investigation

The wooden oars excavated from Wolji, Gyeongju, constitute important archaeological evidence for understanding waterborne activities and woodworking technology during the Unified Silla period. However, little is known about their conservation history, material characteristics, or long-term preservation. This study investigated seven wooden oars through archival research, X-radiography, X-ray fluorescence (XRF) spectroscopy, wood identification, and re-conservation treatment. Archival research reconstructed the conservation and exhibition history of the oars and documented that wooden oars were included in an early conservation program involving polyethylene glycol (PEG) shortly after excavation. However, the surviving records do not permit the PEG treatment history to be linked individually to each of the seven currently registered oars. Two specimens were also documented as having received additional conservation treatment for the 1980 Special Exhibition of Anapji Artifacts, although no records documenting internal structural reinforcement were identified. X-radiography revealed internal metallic reinforcements in six of the seven oars, while qualitative XRF analysis of exposed reinforcement rods in two specimens detected Fe and Cr at the analyzed surfaces. Wood anatomical identification showed that all seven oars were made from Quercus spp., a relatively dense hardwood whose mechanical properties are compatible with the functional demands associated with wooden oars. Based on the results of the condition assessment and technical study, re-conservation treatment addressed deteriorated and unstable areas while preserving evidence of previous interventions wherever possible. By integrating archival research with scientific investigation, this study reconstructs previously undocumented conservation history and provides reference data for the assessment, re-conservation, and long-term management of archaeological waterlogged wooden artifacts.