Numerical Modelling of Moisture Loss during Controlled Drying of Marine Archaeological Wood

Abstract

If left to dry uncontrollably following excavation, marine archaeological wood suffers significant and irreparable damage. Conservation treatments are required to consolidate degraded wood and to remove residual water. Drying must be controlled to eliminate erratic and heterogeneous water removal. Monitoring and understanding the drying process progression is invaluable information to garner real-time knowledge to correlate with chemical and physical material properties, and to develop future conservation strategies. Here, polyethylene glycol (PEG) consolidated marine archaeological wood was periodically sampled during drying to determine the moisture content as a function of location, time, and sample depth. The heterogeneous nature of the material leads to significant noise across spatial and temporal measurements, making it challenging to elucidate meaningful conclusions from visual observation of the raw data. Therefore, the spatiotemporal data was computationally analysed to produce a representative model of the ship’s drying, illustrated by a dynamic simulation. From this we can quantitatively predict the drying rate, determine the depth-dependence of drying, and estimate the resulting equilibrium moisture content. This is the first time such simulations have been carried out on this material and conservation process, demonstrating the power of applying numerical modelling to further our understanding of complex heritage data.

Morphological Study of Bio-Based Polymers in the Consolidation of Waterlogged Wooden Objects

“…The combination of freeze-drying with a consolidant that replaces water and bulks the remaining wood cells, which acts as a cryoprotector during freezing but does not sublime, further reduces damage. The majority of studies on drying behaviour in the presence of consolidants have focused on PEG and the effect of the freeze-drying conditions only [39][40][41][42][43][44][45]. However, conservation of waterlogged wooden and non-wooden objects with the bio-based polymer Klucel (hydroxypropylcellulose, M w = 80,000 g/mol) has been reported and has recently shown its applicability and suitability, as well as that of a range of other alternative polymers, to the freeze-drying process [46][47][48].…”