What Is Weathering and Why Does It Matter?

Before diving into your individual testing plan, it's important to understand the basics. What is weathering? How can weathering impact my product or application? Weathering refers to how materials degrade due to exposure to sunlight, temperature fluctuations, and moisture. During his presentation, Sean highlighted how each factor affects materials:

◆  Sunlight: UV radiation (especially UVA and UVB) is the leading cause of polymer degradation. Variations in sunlight intensity depend on several factors. Most obviously day and night cycles, but other considerations include global latitude position, seasonal variances, and altitude. For products that see sunlight through window glass, the thickness and glass type also play a role on the light intensity and spectrum.

◆ Heat: While sunlight and specifically high energy UVA and UVB photons initiate polymer degradation, temperature can increase the rate of degradation and even cause secondary effects. Additionally, dark colored materials will absorb more light resulting in elevated temperatures, potentially amplifying degradation.

◆ Water: Materials experience moisture from rain, relative humidity, and dew; with the latter often having the biggest impact. Water can facilitate chemical reactions, either directly with the polymer structure or through increased oxidation. Water via rain events can additionally cause erosion of the top layer of materials and create thermal shock.

It's important to note that these weathering forces don't work independently. In fact, they often work in synergy, making a comprehensive weathering testing program essential to simulate the real-world conditions your materials will face.

Why Laboratory Weathering Testing is Important?

While nothing beats natural outdoor testing, laboratory weather testing provides fast and accurate results providing manufacturers with valuable data that can help drive decisions. It helps answer questions such as:

◆ Will the product withstand environmental conditions?

◆ Does it meet customer specifications?

◆ Can costs be reduced without compromising durability?

The Key Categories of Laboratory Weathering Testing

Laboratory weather testing can be broken down into four main categories:

◆ Quality Control: Pass/fail tests with a short-defined duration.

◆ Qualification/Validation: Material specification tests with defined duration and material performance. Typically application and material specific.

◆ Correlative: Open-ended tests comparing materials performance against outdoor benchmarks.

◆ Predictive: Long-term tests requiring significant outdoor & laboratory data to determine service-life predictions.