Light
Light speeds up the oxidation of paper, and thus its chemical breakdown.
It can cause paper to whiten or darken and dyes, pigments, and other colorants
to fade. Light speeds up the detrimental effects of other deteriorative chemical
reactions, such as the release of plasticizers and by-products from unstable
plastics or wood treatments.
Display of individual issues of the magazine may result in fading of the
inks. Most contemporary colored inks are made from synthetic dyes; while
they do not harm paper, they are not permanent. In particular, yellow inks
have a record of fading when exposed to light.
All light is potentially damaging but ultraviolet radiation is the most likely to cause
serious damage. Primary sources of ultraviolet radiation are sunlight and fluorescent light.
Sunlight may contain as much as 25 percent ultraviolet light, while fluorescent bulbs may emit three to seven percent.
A considerable amount of ultraviolet light can be eliminated by the use of UV filters and curtains.
Incandescent lamps are also damaging. These bulbs emit a higher percentage of infrared
light than fluorescents, and have the same effect as high temperature on paper.
Light damage is cumulative, and the amount of damage depends on wavelength, length of
exposure, and intensity. Thus, brief exposure under high intensity can be just as damaging
as extended exposure under low intensity. |
