With its experience in developing high-performance masterbatches and pigments, Chimar provides tailored solutions for creating outdoor products that maintain their beauty, colour, and functionality over time
Summer means outdoor living, relaxing in the sun, and spending time outside. But while a few hours of sun exposure might leave us sunburnt, for plastic, the long-term effects can be even more visible… and permanent.
Have you ever noticed that old garden chair that was once a vibrant red but is now faded and worn out? It’s not just the passing of time to blame — it’s mainly the sun.
The effect of sunlight on plastic: A molecular issue
Ultraviolet (UV) rays, part of solar radiation, are one of the main culprits in the degradation of plastics exposed outdoors.
When they strike the surface of the material, they trigger a process called photodegradation, which can lead to colour changes, cracking, or a loss of mechanical integrity. Coloured pigments in plastics are particularly vulnerable: UV rays break down chromophore molecular bonds—the very structures responsible for colour. This causes a loss of brilliance and turns the surface into something dull and uneven.
The phenomenon is even more noticeable in organic pigments, which—containing carbon atoms—are more prone to oxidation than inorganic pigments.
Not just sunlight: When the environment speeds up fading
Light is only part of the story. Humidity, dust, salt air, and rain are other environmental factors that interact with plastics, altering their appearance and performance.
Imagine two identical objects: one left outdoors on a Tokyo terrace, and the other under the Moroccan sun. Even if both are exposed to sunlight, the different humidity levels, contaminants, and intensity of light will make them age in very different ways.
Geography and solar intensity: Fading happens faster in the tropics
UV intensity varies significantly depending on latitude. It’s no coincidence that the same outdoor furniture will last longer in Northern Europe than its twin on a Mediterranean terrace.
The closer to the Equator, the higher the solar radiation—and the faster the degradation of exposed plastic. Studies and global solar irradiance charts confirm it: The sun doesn’t shine the same everywhere.
How do we test plastic’s resistance to sunlight?
Waiting years to see if a material fades is not an option in the industry. That’s why tools exist to simulate in a few days what would happen in nature over months or years.
We’re talking about accelerated weathering machines, which expose plastic samples to UV radiation (often using xenon arc lamps, which simulate the solar spectrum very accurately) and sometimes to other environmental conditions as well. These tests help predict how a material will perform under prolonged or extreme conditions.
Preventing fading: Pigments and additives as allies
To protect plastic products, there are two main approaches:
1. Choose more resistant pigments
Inorganic pigments provide higher lightfastness than almost all organic ones, making them the preferred choice for outdoor use. However, they offer a more limited and less vibrant colour range.
An interesting option is to create mixed formulations, combining organic and inorganic pigments to balance aesthetics and durability. In some cases, organic pigments can also be treated to improve their light stability. Among the most widely used additives are zinc oxide and titanium dioxide, which help protect the polymer matrix.
2. Add UV stabilizers
Just like sunscreen protects our skin, UV additives protect plastic. These substances are blended into the plastic during production and work by absorbing or deflecting UV rays before they reach the colored pigments.
Light stabilizers such as HALS (Hindered Amine Light Stabilizers) and UV absorbers each have different chemical mechanisms—but one goal: to protect the integrity of the material.
Colour can be protected
Sunlight, humidity, dust, and salt air don’t have to be plastic’s enemies.
With its experience in developing high-performance masterbatches and pigments, Chimar provides tailored solutions for creating outdoor products that maintain their beauty, colour, and functionality over time.
