Dehydration and Effectiveness Evaluation of Waterlogged Archaeological Wood: A Case Study of the Qiantang River Ancient Seawall

The waterlogged archaeological wood from the Qiantang River Ancient Seawall site faces significant preservation challenges due to its unique and complex preservation environment. Without targeted dehydration and consolidation treatments after excavation, these artifacts are at risk of severe deformation, cracking, or even complete destruction. This study focuses on the waterlogged wood from Chaitang (bundled firewood structure) and Zhulong Shitang (bamboo–stone structure) within the ancient seawall, comparing two methods: ethanol dehydration and polyethylene glycol (PEG) dehydration. Both methods were combined with natural drying for comparative analysis. In addition to traditional metrics such as dimensional stability and weight percentage gain, the study employs a multidimensional evaluation framework, including colorimetric analysis, scanning electron microscopy (SEM), and X-ray diffraction (XRD), to comprehensively assess the effectiveness of dehydration and consolidation. Combining natural drying with PEG, although it may reduce the chromaticity of WAW to some extent, effectively fills cellular cavities, enhances diffraction peak intensity, improves dimensional stability, and effectively prevents cracking and deformation. The results provide differentiated treatment strategies for WAW from different historical periods and varying degrees of degradation. This study offers valuable insights and a scientific basis for the further restoration and preservation of the WAW from the Qiantang River Ancient Seawall.