Light Stability & Weather Resistance
Exposure to sunlight and some artificial lights can have adverse effects on the useful life of plastic products. Ultraviolet light, the same type that causes sunburn, can initiate chemical reactions in polymers, which result in discoloration, the breakdown of chemical bonds and loss of chemical and physical properties.

Consequently, polymers used outdoors frequently require UV protection and weather resistant pigments. This can be achieved with plastic additives such as light stabilizers and appropriate pigments

The Ciba light stability significantly extend the lifetimes of many types of plastics, rubbers and fibers. The plastic additive of choice will be specific to the type of plastic and will also depend on the durability and protection requirements of the application and any desired secondary properties (e.g. product form, solubility, compatibility, volatility).

Color is an important consideration in formulating plastics as well. Pigments and Dyes have an intrinsic light stability and further influence the light stability of a polymer product. Ciba has developed a wide range of light-fast pigments for interior and weather-fast pigments for high demanding plastic outdoor applications like stadium seats, bottle crates and automotive components.

Appropriate pigment and polymer additive selection is necessary to ensure long-term performance in outdoor applications. The light stabilization system has to be considered together with the pigment formulation and the determinant failure criteria of the final article.

Once the above variables have been defined, the best way to assess weathering resistance in service is by using outdoor exposure tests in the climatic region(s) concerned. This is clearly not always feasible.

Therefore a number of accelerated weathering tests are widely used to estimate the actual lifetime or durability of plastic or rubber applications.