Mitteilungen des Österreichischen Staatsarchivs 39. (1986)
Archive Buildings and the Conservation of Archival Material. An Expert Meeting, held in Vienna, Austria October 30 - November 1, 1985 - THOMAS, David: Architectural Design and Technical Equipment for the Physical Protection and Conservation of Documents
242 Archive Buildings archivists, however, is the tendency of colour photographic material to fade. Fading is a chemical process which occurs in the dark as much as in the light. It tends to affect the yellow dyes in the image rather than the magenta or cyan. Worst affected are colour prints and transparencies made on substantive films (e. g. Ektachrome). Rather better are silver dye bleach films and prints (e. g. Cibachrome) and transparencies made on non-substantive film (e. g. Koda- chrome). Manufacturers have made real efforts to improve the longevity of their products, but even modem material will show visible fading within 21 years. The problem is that in the next few years, archives are going to be accepting large quantities of colour photographs; the output of colour paper exceeded that of black and white in 1972 and by 1981 it was three times as great41). Inevitably, this is going to affect the amount of colour materials which find their way into archives. This problem affects cinefilm as much as still film and was brought dramatically to public attention by Martin Scorsese the film maker, who went to see Visconti’s Gattopardo, only to find that it had turned pink. It is generally accepted that even carefully preserved film will only have a life of about 25 years42). All audio visual materials are very susceptible to changes in temperature and RH. The rate of fading of colour film is very influenced by these factors. One estimate is that colours will fade 340 times faster if stored at 24° than they would at -18° C43). The hydrolysis of dyes occurs above 30% RH and the rate of fading is twice as fast at 60% RH as at 40% RH44). High RH can also have some other unfortunate effects. The higher the level of humidity, the greater is the risk that residual chemicals in the photographs will affect the image45). Above about 60% there is a risk that mould will grow; this is a particular problem with transparencies, as anyone who has taken photographs in the tropics will testify. Very dry conditions will embrittle the gelatin46). Cycling of RH can have harmful effects. Modem prints consist of a gelatin image layer on a polyethylene coated base; the gelatin changes dimensions much quicker than the base as RH changes and can crack47). Sound recording discs can also be affected by conditions of high RH because mould will grow on some of the compounds which have been used by record manufacturers. Cycling of temperature and RH can have bad effects on sound recording and computer tapes. Such cycling will cause changes in tape dimen41) G. Kolf Modem Photographic Papers in British Journal of Photography 127 (1980) 298. 42) Sight and Sound 50/1 (1980/81) 12. 43) R. J. Tuite Image Stability in Color Photography in Journal of Applied Photographic Engineering 5 (1979) 201. 44) Kodak Preservation of Photographs 40. 45) ISO 6051 section 6.1. ") ISO Photography-Practice for the storage of processed safety photographic film (ISO 5466, 1980) section 7.1.2. 47) T. F. Parsons and others To RC or not to RC in Journal of Applied Photographic Engineering 5 (1979) 112.
