Conservation of Subfossil Bones from a Lacustrine Setting: Uncontrolled and Controlled Drying of Late Quaternary Vertebrate Remains from Cold Lake, Western Canada

Abstract

Water-saturated vertebrate remains (e.g., bone, antler, and ivory) are particularly challenging to stabilize for long-term storage, research, and analysis. These types of specimens are sensitive to damage caused by water loss, which frequently results in delamination, twisting, and cracking. The recovery of late Quaternary vertebrate remains from underwater areas of Cold Lake, western Canada, prompted us to conduct a series of analyses to better understand the preservation of the remains and their susceptibility to damage, and to test different conservation techniques to achieve successful drying. X-ray fluorescence analysis of a sample of specimens revealed that the remains have particularly high iron concentrations, a condition that might have contributed to weaken their structure, further compromising their integrity when drying. Additionally, we found that certain bone elements, such as long bones, are more susceptible to severe surface delamination than others, and as a result these specimens should be monitored more closely during their treatment. Of the four drying methods we tested, controlled air-drying produced the best results, followed by solvent-drying. In contrast, vacuum freeze-drying and vacuum freeze-drying with 20% v/v Acrysol WS-24 in water, an acrylic dispersion, while rapid, resulted in differing degrees of delamination and cracking.