[shvcko99]

This is a line of text I found on a website.

"Research has shown (above) that 40% of fading is caused by UV rays.  Another 25% of fading is due to heat, with 25% being caused by normal visible light.  The remaining 10% cause of fading is from indoor artificial lighting, humidity, and poor dye anchorage.  Visible light and UV radiation cause fading and a lack of moisture, especially in the cloth materials used to cover books."

Is what's said true? I always thought that only sunlight or UV would cause fading. Or does it only apply to certain materials?

[Borek]

It depends on so many factors there is no single, simple answer, covering all cases. Yes, there are plenty of factors, including (not mentioned) atmospheric oxygen.

[wildfyr]

Depends 100% on specifics. Some dyes or pigments are essentially impervious to UV, others are very sensitive. Same for every other factor