What causes prints to fade?
What causes some prints to fade? I understand if something is hung on wall that receives sun, but this is not the case in this situation. A friend of mine got married six years ago, and her pictures are stored in a photo album. I looked at them recently and I was shocked to see how washed out they look. Why?
Unless printed on "archival paper", the chemical dyes in photo prints will break down and fade with time, even if not exposed to the sun. I noticed the same thing in some albums of my grandmother's. There were several pages of prints from the 1960's that were faded to green, while other pages from the same period but printed on a different brand of paper showed little degradation.
|Alan N. Marcus||
You asked for it, don't read this if you don't want to know.
The conventional black & white photographic image consists of metallic silver held in place by a binder of purified gelatin. To date, there is no suitable substitute for gelatin. The conventional color images; slide, negative and print, are also silver based. These images consists of oily dye globules suspended in gelatin
Gelatin is an animal product made from bone and skin. Gelatin is food and thus susceptible to attack by mold and bacterium. All conventional photographic materials should be stored under low humidity conditions as moisture promotes bacterial action.
The black & white silver image is stained brown by sulfur. Airborne sulfur is present due to coal burning and other fuels with high sulfur content. That being said, the modern black & white, if properly processed is good for a century and more. The color image is good for 80-100 years.
Photographers tone black & white prints brown and sepia for expression. However early photographers practiced toning to increase longevity. Toners replace silver with inert metals or pre-tarnish the silver to yield an inert silver compound. Most toned images are very stable and will probably outlast the paper base.
Color images are not as stable. The dyes that must be used are cyan (blue-green), magenta (red-blue) and yellow. No known substitutes. Furthermore, these dyes must be compatible with silver based development and therefore must be in a colorless state until developed. During development the missing ingredient is supplied and the dye is caused to blossom. All three are missing the same ingredient. Consider how difficult it is to find different color dyes that are colorless when missing the same ingredient. Due to this complication, the dyes used are fugitive, meaning they are susceptible to fading.
Digital presents an opportunity to use pigments as well as dye. Look ahead to materials that will last for centuries.
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