Ultraviolet Light

• Most ultraviolet light is emitted from the sun, but halogen and fluorescent lights also emit ultraviolet rays. Ultraviolet light is invisible to the human eye and has a shorter wavelength than the visible light spectrum. Because of its shorter wavelength and higher frequency, ultraviolet light can bombard an object with more energy in a shorter amount of time, making it more damaging than visible or infrared light.
  
  

Photochemical Reactions

• As light is absorbed by ink, it can activate a number of different chemical reactions, depending on its composition. Ultraviolet light has a degrading effect on most polymers, breaking the bonds between molecules. Because most modern inks use polymers in some form or another, often as solvents or lubricants, ultraviolet light will have a damaging effect on ink.
  
  

Damage to Ink

• Most inks, when exposed to ultraviolet rays, will fade or change colors over time due to photochemical reactions. The damage is cumulative over time, which means that every time ink is exposed to ultraviolet light, it will become more and more damaged. Certain inks will hold up better against light damage than others, particularly carbon-based inks.
  
  

Preventing UV degradation

• The best way to prevent light damage to ink is limit its exposure to light. Keep materials away from direct light. If possible, buy or procure ultraviolet-filtering plastic in which to keep papers. If necessary, it is also possible to buy varnishes to put on windows and glass that will filter out ultraviolet rays.