UV absorbers are only really effective in thicker sections as the thicker the section then the greater the chance of the light energy falling on an absorber molecule rather than a polymer molecule. Also, relatively large amounts of absorber have to be added to the polymer to ensure there is enough present to scavenge all of the light energy that falls onto the polymer substrate. These systems have the advantage that they can be used to protect whatever is being covered or packaged by the treated polymer as well as the polymer itself. The most effective and important stabilizers are the hindered amine light stabilizer\ the so-called HALS. Rather than simply absorbing the light energy these work by interrupting the photodegradation process before it can get destructively underway.

Sunlight intensity and composition varies according to latitude, atmospheric effects, etc. so it is important that the additive (or more normally the combination of additives) is selected to suit the exact application. It is therefore important to identify where in the world a final product will be used and the required life span. Other factors that affect the choice of UV stabilization package include product dimensions, type and col our of pigments present, and application information such as food or pesticide contact.