PhD Project: Lifetime of colour photographs in mixed archival collections
A significant problem in the preservation of colour photographs is their inherent instability, which leads to fading of dyes even in the dark. Thus, colour print stability is mainly dependent on the environment conditions during storage. Nevertheless, often photographs are stored in mixed collections, particularly in archives, with the storage conditions often being geared towards the other, more abundant, material. But what are the environmental conditions which are most significant to the degradation of photographic prints, and in what way do these conditions interact together and with the material to cause changes in the photographic material?
This project aims to evaluate the impact of different environmental conditions on colour photographic media stored in mixed collections. By combining material characterisation, environmental conditions and value measurements, the data collected will help in the construction of a computer model which will allow for lifetime prediction, thus assisting in the management of photographic media in these mixed collections.
Main Achievements
- The first task in this project has been to build a reference collection of historic photographs by acquisition and donation. The reference collection has been characterised, and work has been done on the development of a tool for dating colour photographs.
- A survey of environmental conditions, particularly pollutant concentrations, was also carried out at The National Archives. External environments, repository environments and microclimates inside archival boxes were monitored. Acetic acid was identified as the pollutant of greatest concern, being present at concentrations of approximately ten times higher than the most concentrated outdoor-generated pollutants (nitrogen oxides) [1].
- Once the environmental parameters most relevant to photographic degradation were identified, an experimental methodology was developed for simultaneous assessment of the effect of these environmental factors (temperature, humidity and acetic acid concentration) on colour photographs. A colourimetric method for monitoring changes in dye concentration was developed to allow for dye changes to be followed during the degradation process. Using this set-up, acetic acid was also identified as the pollutant which caused the greatest rate of change to colour photographic dyes, in comparison with nitrogen oxides and formaldehyde [2].
- A methodology for gauging the opinion on fitness for purpose of colour photographs during their lifetime has been prepared. Visit the project website for more information on participating in the planned workshops.
Final Outcomes
All the information collected on material stability, environmental data and value changes will feed into a computational modelling tool. This innovative tool will enable us to build a comprehensive model of possible synergistic effects, allowing those entrusted with collections of cultural heritage objects to develop suitable preservation strategies.
Publications
- [1] Fenech, A., Strlic, M., Degano, I. and Cassar, M.: “Stability of Chromogenic Colour Prints in Polluted Indoor Environments”, Polymer Degradation and Stability, 95:12, 2010, 2481-2485.
- [2] Fenech, A., Strlic, M., Cigic, I.K., Levart, A., Gibson, L.T., De Bruin, G., Ntanos, K., Kolar, J. and Cassar, M.: "Volatile Aldehydes in Libraries and Archives", Atmospheric Environment, 44, 2010, 2067-2073.
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