Using supercritical carbon dioxide as a tool for preserving culturally significant items

Hammond, Georgina (2017). Using supercritical carbon dioxide as a tool for preserving culturally significant items. University of Birmingham. Ph.D.

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Abstract

Conservators treat and repair a huge array of damaged and degrading materials on a regular basis. As such, there are many techniques and protocols in place to deal with these problems successfully, be that via preventative or interventive methods. However, there is need for new and innovative techniques that offer long term stabilisation to materials and objects that are prevalent within museum collections. As an alternative to some of these conservation techniques, hydration with supercritical carbon dioxide was investigated here.
Both modern and historic, hardwood and softwood samples were successfully hydrated using this technique. The addition of a co-solvent (methanol) to the supercritical fluid solvent stream was used as a method to increase the solubility of water in carbon dioxide, and therefore improve levels of hydration. To evaluate the extent of any damage being caused during the supercritical fluid treatment, microstructural and macrostructural analytical techniques were carried out. The supercritical hydration technique allowed historic wood to be hydrated and stabilised. Strength properties were seen to be maintained or improved after the supercritical treatment, providing conservators with a viable method of hydration.
A feasibility study looking at the cleaning and characterisation of historic leather samples was investigated using spectroscopic methods. The sensitivity of Diffuse Reflectance Infrared Fourier Transform spectroscopy on historic leather was explored. Additionally, changes in elemental composition on the surface of the leather were monitored using Scanning Electron Microscopy Energy Dispersive spectroscopy. Cleaning historic leather via a supercritical carbon dioxide solvent stream showed the greatest potential for future work. However, the characterisation of unattributed historic leather is a vast and complex task that would require the expertise of a leather conservator, if the investigation were to be continued.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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