WPC Weathering Testing

To ensure the outdoor durability of WPC products, many manufacturers have developed their own weathering test protocols, often based on the international standard for plastics weathering, ISO 4892-2. This standard specifies exposure to xenon-arc radiation, simulating the full spectrum of sunlight, including UV radiation, visible light, and infrared. Important for realistic test temperatures and color degradation.

Due to their wood fiber content, WPC products are particularly sensitive to water, which can lead to swelling, deformation, and also influence color change. Therefore, applying relatively high humidity levels (≥50%) and/or extending the duration of water spray periods during testing may be useful. For example, extending the water spray period from 18 minutes every 2 hours to 30 minutes every 2 hours can provide a more rigorous assessment of WPC’s durability.

SUNTEST XXL and Test Settings

The SUNTEST XXL is probably the most practical xenon-arc instrument for WPC weathering. In addition to its size, its 5° inclined test plane is an advantage. This allows for realistic wet times after water spray periods, closely mimicking real world conditions for horizontal / near horizontal applications.

The following is an ISO 4892-2 weathering test setup adjusted for WPC products using the SUNTEST:

• Optical Daylight filter
• Irradiance: 60 W/m² (300-400 nm)
• Test temperature: CHT 38°C, BST 65°C
• RH: ≥50%
• Water sprays: 102 dry / 18 water spray; more intense: 90 dry / 30 water spray

Test durations range from 4000 to 8000 hours. WPC products that show minimal change after such xenon-arc weathering can be expected to last several years, even in challenging hot and humid outdoor environments.

More Information

For further guidance on testing polymer-based products, please see our Polymer Weathering Standards Guide.

For more information, check out videos and tutorials, download technical articles, or register for an educational class.