Post-treatment Study of Iron/Sulfur-containing Compounds in the Wreck of Lyon Saint-Georges 4 (Second Century ACE)

An innovative bio method was investigated to extract harmful iron and sulfur species from waterlogged wood samples. The method was compared with a chemical treatment. Both approaches were applied on lacustrine and marine samples, from different wood genera, to evaluate the versatility of the proposed bio method. Non-invasive and non-destructive methods were carried out to investigate both bio-based and chemical treatments. The result was that some wood genera were more affected by the bio approach, with a clear distinction between lacustrine beech and pine against oak and lime wood species. The chemical approach showed potential harm for the wooden structure, with acidic pH values and an increase of maximum water content, both implying degradation of the wood structure. In terms of extraction, no iron or sulfur products were detected by Raman spectroscopy on biologically treated samples, in agreement with extraction rates calculated. It was also suggested that iron bonded to wood was extracted with the chemical approach, and calcium content affected by both approaches.

Section: Iron Extraction Efficiencymentioning

confidence: 85%

Assessing the Versatility of Bioextraction to Preserve Waterlogged Wood

Monachon,

Pelé-Meziani,

Ganesan

et al. 2023

“…5-20 µm in diameter) made up of numerous smaller individual crystals (also smaller than 1 µm) (Figure 9c). The shape of the inclusions, namely framboids, and their composition may indicate iron sulphides, like pyrite or marcasite [55,56].…”

Section: Mineral Inclusionsmentioning

confidence: 99%

Scanning Electron Microscopy Protocol for Studying Anatomy of Highly Degraded Waterlogged Archaeological Wood

Balzano

Merela

Čufar

2022

Waterlogged archaeological wood (WAW), approximately 4500 years old, from the prehistoric pile-dwelling settlement at Ljubljansko barje, Slovenia, was examined by scanning electron microscopy (SEM). We propose a simplified protocol for sample preparation and the SEM technique for the study of highly degraded WAW of Quercus, Faxinus, Acer, Salix and Populus, representing taxa with different wood properties. We present the advantages of the proposed technique for wood identification, the observation of various anatomical features and for the study of cell wall degradation. SEM, equipped with energy-dispersive X-ray spectroscopy (EDX), allowed us to detect significant amounts of Fe, S and Ca with different appearances, amounts and distributions in the wood of the studied taxa. In the case of Populus, an increased amount of Si was also detected. The applied SEM protocol allowed characterisation of the anatomy of the highly degraded WAW while reducing the time required for sample preparation and examination under the microscope, as well as extending the lifetime of the SEM components (e.g., tungsten filament), compared to the situation when we analyse wood samples with a greater volume.

“…Other suggested methods for iron removal prior to consolidation include electrophoresis [183] and microbial-mediated extraction [181,184]. Although soluble iron salts can be removed from waterlogged wood prior to conservation, iron sulphides are much more intractable [185]. An alternative approach is to accept the continued presence of iron and sulphur compounds, but prevent the ingress of oxygen by the application of a suitable gas-impermeable coating or envelope [55].…”

Section: Degradation Of Consolidated Woodmentioning

confidence: 99%

Conservation of Waterlogged Wood—Past, Present and Future Perspectives

Broda

Hill

2021

This paper reviews the degradation, preservation and conservation of waterlogged archaeological wood. Degradation due to bacteria in anoxic and soft-rot fungi and bacteria in oxic waterlogged conditions is discussed with consideration of the effect on the chemical composition of wood, as well as the deposition of sulphur and iron within the structure. The effects on physical properties are also considered. The paper then discusses the role of consolidants in preserving waterlogged archaeological wood after it is excavated as well as issues to be considered when reburial is used as a means of preservation. The use of alum and polyethylene glycol (PEG) as consolidants is presented along with various case studies with particular emphasis on marine artefacts. The properties of consolidated wood are examined, especially with respect to the degradation of the wood post-conservation. Different consolidants are reviewed along with their use and properties. The merits and risks of reburial and in situ preservation are considered as an alternative to conservation.