Color materials in photography change over time because they are made with organic dyes.

In modern biological analysis, various kinds of organic dyes are used.

That's because most color images are constructed with three layers of organic dyes.

Alcohol is one of the best solvents for many organic dyes, which by themselves are solids.

Like most organic dyes they are susceptible to degradation by oxygen and free radicals.

Genuine cotton, if she was any judge of these things, stained with organic dyes in bright blue and green.

Most organic dyes will fade if exposed to light for a long enough time.

Whether synthetic or natural, they all use organic dyes.

Just as with proteins, also some organic dyes can change their structure upon illumination.

The ability to fluoresce of such organic dyes can be turned on and off through visible light.