![]() ![]() For extended storage aimed at long-term preservation, cellulose nitrate, cellulose acetate and chromogenic dye photographs require cool (10 – 16 ☌), cold (2 – 8 ☌) or freezing conditions (less than 0 ☌). Temperature control is also critical as higher temperatures will accelerate degradation processes. Table 1: Relationship between storage temperatures and acceptable relative humidity levels: Storage temperature Higher levels of relative humidity can be tolerated if lower storage temperatures are maintained (Table 1, Robb 2004). ![]() Many ink jet prints are particularly susceptible to damage if relative humidity levels exceed 50 %.įor a mixed collection of historical photographic prints, slides and negatives, or if the collection comprises only photographs, keep the relative humidity in the range 30 – 40 % with only a 5 % daily variation. Dyes deteriorate four times faster at 60 % relative humidity than at 15 % relative humidity and halving the relative humidity at which cellulose triacetate bases are stored doubles their life expectancy (Lavédrine 2003). For example, high relative humidity levels may soften gelatin while low relative humidity levels may cause binders to shrink and crack and overall flexibility to be reduced. The effects of varying relative humidity levels are manifold. Keep light exposures at 50 lux or less with minimal exposure to UV radiation. The damaging effects of light are well known. The environment to which photographic materials are exposed is critical to their longevity and preservation. tinted emulsions may fade due to prolonged exposure to light.images on glass are easily scratched and.continual changes in relative humidity may cause silver mirroring.gelatin emulsions are very susceptible to mould attack caused by high humidity.the emulsion layer is particularly attractive to insects as a food source.In addition to suffering the same problems as other paper-based materials, photographic images have other in-built problems. For example, if the image is not well fixed it will eventually blacken, while if residual fixer has been left then the silver image may fade accompanied by yellowing of the image, binder and support (Robb 2004). Significant silver deterioration will occur if photographs are not correctly processed and washed. Aim to improve the environments to which photographs are exposed, encourage appropriate care and handling practices and use archival quality materials for storing and displaying photographs. Unless a particular photograph or photographs are of major significance it is far better to focus attention and resources on improving preventive conservation measures than on costly conservation treatments of deteriorated photographs. the presence of residual processing chemicals and the use of exhausted processing chemicals). poor processing techniques in the original production of some photographs (e.g.the use of poor storage enclosures or housings.storage or display in inappropriate environmental conditions.The major factors that influence the deterioration of photographic materials are (Robb 2004): determine the most appropriate environmental conditions and storage/housing for all photographs in a collection.examine each of the photographs and assess their respective conditions and.identify and document all photographic materials in a collection.In order to appropriately care for photographic collections, it is necessary to: Appendix 9: Spot Tests for Common Metals.Appendix 6: Packing, Storage and Mounting Materials.Appendix 3: Chemical Treatments of Insects.Appendix 2: Environmental Criteria for Materials.Appendix 1: Measuring Light Levels with a Camera.Preventive Conservation: Agents of Decay.Conservation and Care of Collections (2017). ![]()
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