Use of Design-of-Experiment principles to develop a dose-response function for colour photographs

Colour photographs are very vulnerable to the environmental conditions they are stored in. Although ideal conditions of storage have been identified, these conditions are often not appropriate in archival collections. Therefore, it is essential to understand how these environmental conditions affect degradation in order to optimise material lifetime. Such information is typically obtained using accelerated degradation experiments following 'one-factor-at-a-time' methodologies. However, when planned using 'Design-of-Experiment' principles, such experiments provide more information with fewer experimental runs, while information is provided not only on factor effects but also on interactions between factors. This study employed a central composite experimental design plan to develop a dose-response function relating the rate of degradation of dyes in colour photographs to temperature (T), relative humidity (RH) and acetic acid concentrations (c(AA)), which had been identified as the environmental parameters of greatest concern for colour photographs in archival collections: ln(ΔERGBt)=32+0.0002(c(AA))+0.01(RH)−11(1000T). This function now allows managers to appraise various options of environmental management within their collections.