Thermoporometry of waterlogged archaeological wood: Insights into the change of pore traits after the water-removal by supercritical drying

Abstract

Pores of waterlogged archaeological oak wood with different preservation states and maximum water content (MWC) levels were studied in the water-saturated state by DSC thermoporosimetry and then in the supercritical dry state by N2 adsorption and mercury porosimetry. Thermoporosimetry results showed that waterlogged archaeological wood was typical for an extremely large number of pores inferior to 20 nm in size, and macropores prevailed. Micropore, mesopore and macropore volumes of waterlogged archaeological wood with MWC of 460 ± 31% were 723%, 687% and 424% higher than those of waterlogged recent wood. After water-removal, pore became less noticeable, leading to the lower number and area of three pore styles, i.e. micropores, mesopores and macropores. Mesopore cumulative volumes of archaeological wood decreased 70.3%, 62.7% and 42.4% respectively. Linear correlations were found between MWC and meso/macropore volume measured in the water-saturated state. Results illustrate pore traits of waterlogged archaeological wood could be significantly affected by water-removal.