How UV additives work
The reaction of sunlight with the coloring of a material causes a fading of the shades. This color reduction occurs over time through a reaction between the UV rays and the atoms of the coloring. When ultraviolet light hits a colorant, the electrons get excited. These excited electrons are more volatile and prone to oxidizing, eventually causing the coloring to fade.
Additives include anything added to the polymer to prevent the speed and degree of this damage. UV stabilizers, quenchers, and absorbers are among those in this category of additives. Some of these prevent UV light from reaching the coloring, while others jump into the middle of the process to stop it before it leads to long-term wear and fading.