Temporary solidification and extraction of marine archaeological wood underwater at a depth of seven meters: A further contribution.

• The study was conducted in a seven-meter-deep pool wherein the waterlogged ship wood from the "Nanhai I" shipwreck was extracted. • The use of veratraldehyde in underwater archaeology has the potential to revolutionize the field by providing a new method and material for temporary solidification. • The proposed extraction method can safely extract the fragile ship woods underwater. • A set of scientific techniques were proposed for successful in-situ solidifying and extraction of underwater fragile wooden artifacts. In-situ solidifying extraction of large-volume and severely damaged underwater fragile artifacts is still one of the major issues in underwater archaeology. Recent evidence suggests that veratraldehyde can be used to temporarily solidify artifacts underwater; however, it is still challenging to use it in actual archaeological sites. This prospective study was conducted in a seven-meter-deep pool wherein veratraldehyde was used to solidify and extract waterlogged ship wood from the "Nanhai I" shipwreck. The entire underwater extraction process was recorded using a camera. The change in the wood surface color before and after extraction was relatively minor. Scanning electron microscopy analysis revealed that the wood microstructure was not significantly damaged, while nuclear magnetic resonance analysis showed no residues of veratraldehyde and its oxidation products. Overall, the proposed method utilizes a set of scientific techniques for successful in-situ solidifying extraction of underwater fragile wooden artifacts. [ABSTRACT FROM AUTHOR]