Investigating the processes necessary for satisfactory freeze-drying of waterlogged archaeological wood

Jones, Samuel P.P.; Slater, Nigel K.H.; Jones, Mark; Ward, Kevin; Smith, Andrew D.

doi:10.1016/j.jas.2009.05.028

Cited by 25 publications

(14 citation statements)

References 6 publications

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“…Collapse results in abnormal deformation of Eucalyptus cells at the stage of high moisture content (MC) [20]. Specific drying methods can reduce the collapse, such as steaming pretreatment [21], freeze-drying [22], supercritical CO 2 drying [9,15]. Due to the lumen water expulsion during SCD, the microstructure changes caused by capillary tension can also be reduced, which plays a certain role in preventing wood collapse [15].…”

Section: Introductionmentioning

confidence: 99%

Drying Characteristics of Eucalyptus urophylla × E. grandis with Supercritical CO2

et al. 2020

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Supercritical CO2 (ScCO2) is a drying medium with excellent solubility and mass transfer efficiency. Supercritical CO2 drying (SCD) can remove the water of wood rapidly and prevent a change of microstructure caused by capillary tension in the drying process. In this study, Eucalyptus urophylla × E. grandis specimens with lengths of 50 and 100 mm were dried with ScCO2. Conventional kiln drying (CKD) and oven-drying (OD) were used as control. After 1 h, the drying rate, shrinkage, moisture distribution, drying stress were measured to explore the influence of drying methods and specimen length for drying characteristics during the early drying stage. The results showed that compared with CKD and OD, water removal was the fastest under SCD, and the drying rate was nine times of CKD and one time of OD. The shrinkage of SCD was the lowest among the three drying methods. Moisture distribution of SCD and OD was uneven. The drying stress of SCD was relatively high, the drying stress index of it was almost five times of CKD and three times of OD. Regardless of the drying method, shorter specimens had a shorter drying period but greater drying defects than the long specimens.

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Section: Introductionmentioning

confidence: 99%

Drying Characteristics of Eucalyptus urophylla × E. grandis with Supercritical CO2

et al. 2020

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“…In order to prevent the collapse of the treated wooden artefact, it is necessary to keep the temperature inside the object lower than the eutectic PEG-water solution, so that there are no liquid phases present and only sublimation of the ice occurs [104,133]. The presence of liquid phases during the sublimation of the ice would give rise to the capillary forces which cause the collapse of the wood structure [12]. Problems arise because these necessary conditions can result in very long drying times for large objects, with low temperatures required in order to maintain a solid PEG/water phase, but higher temperatures being favourable to more rapid drying and careful optimisation is required to minimise costs.…”

Section: Properties Of Consolidated Wood 41 Drying Of Consolidated Woodmentioning

confidence: 99%

“…Their mechanical properties are generally improved, including the modulus of elasticity and the maximum load of samples in the bending test; however, the samples are more brittle than treated with xylitol [199,200]. The treated wood is often slightly darker in colour; its surface can be sometimes covered with a varnish-like coating or crystalline deposits, which can be easily removed with a damp tissue or gentle brushing [12,197,198]. It was shown that sugar crystals fill the cell lumina of fibres and parenchyma cells, leaving the vessels' lumina empty [198].…”

Section: Trehalosementioning

confidence: 99%

“…Due to the nature of conservation work: preserving the dimensions and appearance of ancient artefacts and making their history accessible to the public, treatments must be "gentle" in order to inflict as little damage as possible to the objects themselves. This often means long timescales and processes governed, for example, by diffusion of chemical treatments into artefacts lasting for periods of up to a year for immersion of smaller objects in tanks or, as for the Mary Rose, a spraying programme lasting over twenty years [12].…”

Section: Introductionmentioning

confidence: 99%

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Conservation of Waterlogged Wood—Past, Present and Future Perspectives

Broda

Hill

2021

Forests

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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.

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“…To the best of the author's knowledge the long-term effects of freeze-drying dendrochronological specimens have not been studied, but some investigations for archaeological materials have been conducted (e.g. Jones et al 2009). Note: freezedrying is often combined with the use of polyethylene glycol, which may be necessary if cellulose remains or to prevent excessive distortion (Hamilton 2000).…”

Section: Waterloggedmentioning

confidence: 99%

Basic Principles and Methods of Dendrochronological Specimen Curation

Creasman¹

2011

Tree-Ring Research

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Investigating the processes necessary for satisfactory freeze-drying of waterlogged archaeological wood

Cited by 25 publications

References 6 publications

Drying Characteristics of Eucalyptus urophylla × E. grandis with Supercritical CO2

Drying Characteristics of Eucalyptus urophylla × E. grandis with Supercritical CO2

Conservation of Waterlogged Wood—Past, Present and Future Perspectives

Basic Principles and Methods of Dendrochronological Specimen Curation

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