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close this book Prevention and treatment of mold in library collections with an emphasis on tropical climates: A RAMP study
close this folder 3. Implications for library materials
close this folder 3.1 Vulnerability of materials
View the document 3.1.1 Paper - cellulose, sizes, coatings
View the document 3.1.2 Bookcloth
View the document 3.1.3 Leather
View the document 3.1.4 Adhesives
View the document 3.1.5 Film and related materials

3.1.5 Film and related materials

All photographic materials have in common a substrate of gelatin which carries the emulsion of silver halide particles that produce the image. The film base may be nitrate, acetate, polyester, glass or paper and the format may be a negative, a photograph, or a reel of microfilm, but all have a gelatin layer. As with the gelatin sizes used in paper, photographic gelatin provides a nutrient for mold growth, which can penetrate the emulsion layer, damaging the image. The polymers that provide the base for contemporary film stock are generally very resistant to fungal attack,6 however paper and glass supports are both vulnerable. Glass plate negatives can actually be etched by fungi, and combined with the damage to the silver halide layer, can render the negative completely useless.

Gelatin is relatively stable as long as it is kept dry. In high humidities gelatin begins to swell and if exposure is prolonged, becomes sticky. This can occur at relative humidities as low as 60%.7