What Effect Does Sunlight Have on Rubber Ink and Paper?

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Sunlight will cause ink and paper to fade. Rubber that has been exposed to sunlight cracks eventually, and bleaching of paper by sunlight occurs because of the ultra violet energy of the sun. Since ink has chemical pigments, exposure to UV radiation causes it to oxidize and lose color; UV light is known to cause loss of color in clothes and magazines.

As Rubber Chemistry and Technology explains, vulcanized rubber that is exposed to sunlight develops a network of shallow cracks, usually under no mechanical stress. The effect of sunlight and mechanical tension can cause deeper cracks in rubber. However, the exposure of raw rubber to sunlight causes it to become sticky.

Elastomers such as rubber experience oxidative degradation, which is catalyzed by UV when exposed to sunlight. The UV in sunlight manages to overcome a C-H bond, producing a radical species that can react with oxygen to trigger the same sequence of reactions as with direct oxidation. Light-catalyzed oxidation in rubber causes it to lose elasticity, thicken and crack in random patterns.

Rubber may also degrade on exposure to ozone when subjected to sunlight. The chemical and mechanical processes for ozone degradation differ from those for light-induced cracking of rubber.