Imaging and Assessment of the Microstructure of Conserved Archaeological Pine

Abstract

Impressive wooden objects from past cultures can last for centuries or millennia in waterlogged soil. The aim of conservation is to bring the more or less degraded waterlogged archaeological wooden (WAW) finds to a stable state without altering the wood structure through shrinkage, collapse, and deformation. In this study, the most used methods in the conservation practice, such as the alcohol-ether resin method, conservation with the melamine formaldehyde resin Kauramin 800, a mixture of lactitol and trehalose, saccharose, silicone oil, and three different conservation methods with polyethylene glycol followed by freeze-drying were tested. The effects of the conservation agents on the structure of archaeological pine were investigated using optical light microscopy (reflected light microscopy, RLM), scanning electron microscopy (SEM), and X-ray computed tomography (XCT). Through the examinations, most conservation agents could be identified in the structure and their impact on conservation could be analyzed. In particular, it was possible to trace the incorporation of the conservation agents in the lumen, which was influenced by factors, such as wood anatomy, degree of degradation, and drying process. Differences in the mode of action of the conservation processes could also be identified in the composition of the cell wall tracheids.

A multi-technique and multiscale comparative study on the efficiency of conservation methods for the stabilisation of waterlogged archaeological pine

“…A considerable variability of the conserved vessels were documented here. The influence of the degradation state and nature of the remaining cell wall has also been observed in other studies 53 , 57 .…”

“…Instead, the total bath concentration played a more significant role, with PEG2 having a concentration of 35% and PEG3 having a concentration of 28%. Synchrotron µCT examinations of this particular sample revealed bright areas, indicating the presence of inorganic components from the soil environment 56 , 57 .…”

“…As the solution evaporates, capillary forces lead to the transportation of the conservation agent. This results in the accumulation of conservation agents within the latewood tracheids with smaller volumes 57 . This accumulation is also apparent in the notably high bulk density of the samples treated with lactitol/trehalose and saccharose (cf.…”