The Viscoelastic Behaviour of Waterlogged Archaeological Wood Treated with Methyltrimethoxysilane

Effect of the Longitudinal Tensile Creep on the Stiffness of Radiata Pine (Pinus radiata D. Don)

The influence of load on the cellulose microfibrils of single cells or thin wood foils is known. It can decrease the cellulose microfibril angles and, in turn, increase the stiffness. However, this modification of a piece of wood, which is made up of multiple cells, is unknown. The aim of this research was to study the effect of tensile creep on the longitudinal stiffness of radiata pine wood. The modulus of elasticity of each specimen was determined before and after being subjected to tensile creep. The samples were loaded at 1170 N and 1530 N for 20 min at 70 °C. The load was determined as a function of a percentage of the force at the proportional limit. The moduli of elasticity before and post-tensile creep showed no effect on the stiffness of wood at the macroscopic level, but neither were there damage to the cell structure. It can be assumed that there are changes at the microscopic level, but they are not enough to be reflected at the macro scale. It is also challenging to achieve the modifications that occur at the level of a single cell or in thin wood foils; however, the implications of this would be favorable for the development of stronger wood-based products.

Stabilisation of waterlogged archaeological wood: the application of structured-light 3D scanning and micro computed tomography for analysing dimensional changes

Cultural heritage objects made of wood can be preserved under waterlogged conditions for many years, where decay is slowed down and the wood structure is more or less completely filled with water. Depending on the degree of degradation, finds may collapse and shrink when they are allowed to dry in an uncontrolled manner after excavation, leading to total loss of the object and its information. Conservation measures are taken to prevent damage of objects and dimensional stability is an important criterion. In this study, structured-light 3D scanning and micro-computed tomography were used to analyse the dimensional stability of wood after conservation, as well as its long-term stability. 83 samples from a reference collection established between 2008 and 2011 allowed this comparative study of the most common conservation methods at that time. The effects of conservation methods using alcohol-ether resin, melamine-formaldehyde (Kauramin 800^®), lactitol/trehalose, saccharose, and silicone oil on dimensional stability were investigated. In addition, different polyethylene glycol (PEG) treatments with subsequent freeze-drying were also investigated: one-stage with PEG 2000, two-stage with PEG 400 and PEG 4000 and three-stage with PEG 400, PEG 1500 and PEG 4000. The data received from analyses of both volume and surface gave detailed information about the success of each conservation method. Attempts were made to quantify the damage patterns, specifically shrinkage, collapse, and cracks. While PEG and freeze-drying, alcohol-ether-resin, as well as the Kauramin 800^® method gave the best results, analysis also highlighted the failures of each method.

Sustainability in Heritage Wood Conservation: Challenges and Directions for Future Research

Conserving the world’s cultural and natural heritage is considered a key contributor to achieving the targets set out in the United Nation’s Sustainable Development Goals, yet how much attention do we pay to the methods we use to conserve and protect this heritage? With a specific focus on wooden objects of cultural heritage, this review discusses the current state-of-the-art in heritage conservation in terms of sustainability, sustainable alternatives to currently used consolidants, and new research directions that could lead to more sustainable consolidants in the future. Within each stage a thorough discussion of the synthesis mechanisms and/or extraction protocols, particularly for bio-based resources is provided, evaluating resource usage and environmental impact. This is intended to give the reader a better understanding of the overall sustainability of each different approach and better evaluate consolidant choices for a more sustainable approach. The challenges facing the development of sustainable consolidants and recent research that is likely to lead to highly sustainable new consolidant strategies in the future are also discussed. This review aims to contribute to the ongoing discussion of sustainable conservation and highlight the role that consolidants play in truly sustainable heritage conservation.