Luisa Casella, Andrew W. Mellon Research Scholar in Photograph Conservation, Metropolitan Museum of Art
Based on her work previously presented at PMG and VERY significant to the field. This presentation outlined the autochrome process and degradation problems. Introduced in 1907 -1935 – Lumiere Company. Conservation issues – physical fragility and sensitivity to temperature, relative humidity and light. Research led by Bertrand Lavedrine.
Current policy is NOT to display autochrome plates. True of many cultural instiutions. Dyes identified are listed.
Dyes must be tested under anoxia conditions. Light fading of each dye required. Dyed starch samdwiched between varnish and on glass plus dyes in filter paper tested as well as historical samples and varnish layers on glass without dyes. Spectophotometric data gathered.
Carefully prepared anoxia set up described. The caps failed originally but this challenge was addressed. 54 days in light fading unit or 2000lux for 9 hours per day over 7 months was equivalent exposure. Full light exposure change noticeable more in oxygen than in argon. Varnish layers were protective. Setoglaucine demonstrated most change in OX and AR. This is the most light sensitive dye in the screen. (blue violet).
Analysis of these samples are interesting. Yellowing under anoxic conditions are visible. Changes at all levels of light exposure. Varnish changed much less under argon conditions. Greater degree of yellowing with sample exposed in OX. Auto-oxidative degradation – similar to that documented in paintings conservation literature. Increasing fluorescence of unprotected areas – i.e. those areas exposed to light.
Overall change is reduced under anoxic conditions. Extensive silver mirroring present under ageing and oxygen exposure. Very interesting and unexpected.
Benefits of using anoxic conditions possible. Sealed package designed. This work is in progress. Historical plates – unexposed – used with the layer of silver removed. Oxygen scavengers used and aluminum film on the edge.
No UV. No heat. Good white balance. Low energy such as LEC Panel from E-lite tested. More neural light possible. NOT bright enough for rendering details of the autochrome. Lite Pad resulted in excessive heat. Care should be taken in using this in a display case. OLEDs may be promising but were not tested here as they are not available in the US yet. Anoxia reduced light fading within certain limits of light. Confirmation of extreme light sensitivity of these dyes is clear.
Can we look at specific wavelength that cause fading and can these be excluded? This is being investigated.