Introduction to Weathering

What is Weathering?

Weathering refers to the process by which materials degrade over time due to exposure to natural environmental forces, including sunlight, heat, and water. This degradation can result in a wide range of changes to the material properties, such as fading, cracking, yellowing, and loss of strength. These environmental factors, often referred to as the “Forces of Weathering,” act together to break down materials over time.

 
Different temperatures

Weathering is driven primarily by three key forces:

  1. Sunlight: Sunlight, particularly ultraviolet (UV) light, plays a significant role in material degradation. UV radiation, despite representing only a small percentage of the sun’s total energy, is responsible for most of the damage seen in polymers and coatings, causing them to lose their strength and appearance over time.

  2. Heat: High temperatures, particularly in areas with large temperature fluctuations, can accelerate the breakdown of materials. Heat causes thermal expansion and contraction, which can weaken the structural integrity of materials and speed up their degradation when combined with sunlight or moisture.

  3. Water: Water in its various forms—humidity, rain, or condensation—can impact materials in multiple ways. It may promote chemical reactions, such as corrosion or hydrolysis, and also contribute to physical effects like erosion, freeze/thaw damage, and water absorption, all of which can accelerate weathering.

These forces of weathering affect a broad range of industries worldwide. Whether it's paints, coatings, plastics, fabrics, or building materials, any product exposed to the outdoor environment can experience some form of degradation due to weathering.

The Importance of Lightstability

Lightstability (or lightfastness) refers to a material's ability to resist degradation from sunlight and heat. Unlike weathering testing, lightstability testing typically excludes the effects of water, making it more applicable for materials used indoors, such as textiles or wallpapers. While both weathering and lightstability testing measure how materials perform under environmental conditions, understanding both helps manufacturers ensure their products will maintain their appearance and performance over time.

Sun Rays

How Do We Test for Weathering? 

To determine how materials will withstand the effects of weathering over time, weathering testing is essential. Through testing, manufacturers can predict how products will perform when exposed to sunlight, heat, and moisture in real-world conditions.

There are two main types of weathering testing:

Accelerated Laboratory Testing

While natural outdoor testing provides valuable data, it can take years to observe significant material degradation. Accelerated weathering testing simulates the effects of sunlight, heat, and moisture in a controlled lab environment, speeding up the process to provide faster insights into material durability. Tests like fluorescent UV or xenon arc simulations replicate outdoor exposure and help manufacturers obtain quicker, repeatable results. 

Two common methods are:

  • Fluorescent UV Testing (QUV): Exposes materials to cycles of UV light and moisture, simulating sunlight and dew with controlled conditions.
  • Xenon Arc Testing (Q-SUN): Uses xenon arc lamps to mimic full-spectrum sunlight, offering precise control over temperature and humidity.

Natural Outdoor Testing

This involves exposing materials to real environmental conditions to observe how they behave over time. Natural outdoor testing provides highly accurate and realistic results, as materials are subjected to actual weather patterns, including sunlight, temperature fluctuations, and moisture.

Recommendations for Natural Testing:

  • Utilize benchmark sites to accelerate results cost-effectively.
  • Start regular tests to build comparative data for new formulations and competitors.
  • Validate lab tests with outdoor data.

Accelerated Outdoor Testing

Accelerated outdoor testing offers a unique combination of real-world environmental exposure and the speed of laboratory testing. This approach utilises specialised equipment such as the Q-TRAC Natural Solar Concentrator and the Automotive Interior Materials (AIM) box to provide valuable insights into material performance under intensified outdoor conditions.

Q-TRAC Solar Concentrator
The Q-TRAC system harnesses actual sunlight to test the durability of materials designed for long-term outdoor use. It features an array of 10 mirrors that focus and intensify full-spectrum sunlight onto test specimens while continuously tracking the sun's movement throughout the day. This ensures maximum exposure, accelerating the effects of natural sunlight. Additionally, the Q-TRAC system includes a water spray feature that can replicate Florida’s humid climate or induce thermal shock to further assess material resilience.

AIM Box Testing
AIM box testing is specifically designed to evaluate automotive interior materials by exposing them to elevated temperatures and natural sunlight filtered through clear or laminated glass—closely replicating the conditions inside a vehicle. These test units also follow the sun's path throughout the day, optimising solar exposure and enabling a more accurate simulation of real-world automotive environments.

By combining both natural outdoor testing and accelerated laboratory testing, manufacturers can gain a well-rounded understanding of how their materials will perform in various environments.

Why Perform Weathering Testing? 

Weathering TestingThere are several compelling reasons to perform weathering testing on your products: 

  • Improved Durability: Weathering tests provide valuable insights that help manufacturers enhance the durability of their products, ensuring they can withstand the elements over time. 
  • Cost Savings: By selecting the right materials that are naturally resistant to weathering, manufacturers can reduce costs associated with failures, replacements, and repairs, thus increasing overall product value. 
  • Prevent Field Failures: Testing ensures that materials won't fail prematurely in real-world conditions. This helps prevent costly warranty claims, product recalls, and damage to the brand’s reputation. 

Ultimately, weathering testing ensures that products perform as expected when exposed to the forces of nature, giving manufacturers the confidence that their materials will stand the test of time. 

Types of Weathering Tests

Understanding the different types of weathering tests is essential to developing an effective testing program. Each test type serves a distinct purpose, and selecting the right approach depends on the specific insights required. Weathering tests can be categorized from the simplest to the most complex, each offering unique benefits.

Quality Control TestingAccelerated Test Types-1
Most weathering tests initially focus on quality control—short, standardized screening tests conducted over fixed time intervals to produce clear pass/fail results. These tests help ensure consistency in production and compliance with basic performance standards.

Qualification and Validation Testing
These tests go a step further by verifying whether a product meets specific customer or regulatory requirements. Successfully passing qualification tests is often necessary for product approval and market entry.

Correlative Testing
Correlative testing leverages outdoor exposure data to establish a ranking system for materials tested in the laboratory. By comparing lab results with real-world performance, this approach helps identify the most weather-resistant materials and detect potential weaknesses.

Predictive Testing
Predictive testing aims to estimate a product’s expected service life based on laboratory data. However, this method is highly dependent on the material, test conditions, and failure modes, requiring extensive outdoor exposure data to validate its accuracy.

Developing a comprehensive test program that combines multiple test types ensures a thorough evaluation of material durability and performance, helping manufacturers make informed decisions and enhance product longevity.

Correlation

Weathering testing is essential for evaluating the durability of materials exposed to outdoor conditions such as sunlight, heat, and rain. The most common question we encounter is: "How many hours of laboratory testing equate to years of real-world exposure?"

While this may seem straightforward, the answer is complex. Natural conditions, including shifting weather patterns, varying humidity, and sunlight angles, cannot be accurately replicated in a lab. Furthermore, the concept of reciprocity—intense testing leading to accelerated results—does not always apply, as different light sources affect materials in varying ways.

Although no definitive solution exists, combining laboratory testing with outdoor exposure data provides valuable insights into material durability. This data helps identify which materials will endure and which may fail, guiding more informed decisions in product development.

Ultimately, weathering testing is about navigating these complexities to create products that can withstand environmental forces, ensuring greater durability and reliability.

Blog Articles

WeatheringWhat is Weathering and Why is it Critical for Material Durability?

Weathering is the process by which materials degrade due to environmental factors like UV radiation, moisture, and temperature changes. In this blog, we explore:

  • The science behind weathering and the key environmental factors driving it.
  • Real-world examples of weathering, such as faded paint, cracking plastics, and rusted metals.
  • Why addressing weathering is crucial for safety, cost-effectiveness, and sustainability.

Read More

Industries Affected by Weathering7 Industries Most Affected by Weathering—and How They Tackle It

Weathering presents unique challenges across various industries. This blog highlights:

  • The top industries impacted by weathering, including automotive, construction, and renewable energy.
  • Strategies these industries use to combat environmental damage.
  • How advanced weathering testing solutions, like those from Thermoline, are enabling better product durability and performance.

Read More

Case Studies

Outdoor plastic chairs
Case Study: Improving Outdoor Furniture Durability through Correlative Testing

A furniture manufacturer faced product failures despite passing lab tests. Q-Lab’s comparison of Q-SUN and QUV testing showed that QUV better simulates outdoor conditions. The manufacturer now uses both testers for improved durability and product quality.

Read More

Wall Adhesive small
Case Study: Testing Yellowing Failures in Adhesives and Fillers

A manufacturer of adhesives faced yellowing failures in the field, especially in the Middle East. Q-Lab’s testing showed that QUV better simulated these issues, leading the manufacturer to invest in a QUV tester for product reformulation.

Read More

Webinars

31Essentials of Laboratory Weathering

Weathering and light exposure are significant factors in the degradation of coatings, plastics,...

 

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32QUV Live Operator

QUV accelerated weathering test chambers replicate the damage caused by ultraviolet light, heat,...

 

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Laboratory with play buttonCorrelation in Accelerated Weathering Testing

Accelerated weathering testing is a widely used method to quickly assess the durability of...

 

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33Q-SUN Operator Training

Q-SUN Xenon Arc Test Chambers are designed to replicate the damage caused by full-spectrum...

 

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Industries & Applications for Weathering

Additives and Colorants

Why Test?

Colorants and additives exposed to sunlight, moisture, and heat are vulnerable to the damaging effects of nature. Some additives are specifically designed to protect base polymers from weathering and corrosion.

Adhesives and Sealants

Why Test?

As customers expect long-term durability of these products, testing helps assess the outdoor durability of adhesives and sealants against sunlight, heat, and moisture. It ensures new products meet performance standards and identifies any process changes that may impact long-term durability.

Architectural and Window

Why Test?

Building materials must endure for years without failure, and warranty concerns can pose significant risks. Weathering testing helps verify the outdoor durability of your products, ensuring consistent quality and identifying any process changes that may affect performance.

Automotive

Why Test?

The automotive industry involves a diverse range of materials that must meet strict outdoor durability standards in a fast-paced, cost-sensitive market. Interior products must endure constant light and high temperatures, while vehicles face the damaging effects of sunlight, heat, and moisture.

Electronics

Why Test?

Durability is key to the cost competitiveness of photovoltaic (PV) panels and wind turbine blades. Understanding factors that degrade energy output, like prolonged outdoor exposure and solar thermal loading on electronic components, is essential for manufacturers.

Fabrics and Textiles

Why Test?

Textile materials can lose color and tensile strength when exposed to sunlight, both outdoors and through window glass, as well as in high-humidity environments.

Graphic Arts

Why Test?

Printed products exposed to sunlight, moisture, and heat face the damaging effects of weathering, while indoor materials are affected by artificial lighting and sunlight through windows.

Home and Consumer Goods

Why Test?

Colorants, flavorings, fragrances, and other additives are sensitive to exposure to both natural sunlight and indoor lighting. Since consumers can easily detect changes in taste, color, or fragrance, it’s crucial for manufacturers to ensure light stability while avoiding excessive use of costly photodegradation-protective additives.

Paints and Coatings

Why Test?

Exterior paints and coatings face the damaging effects of sunlight, heat, and moisture, and customers expect exceptional long-term durability against these elements.

Pharmaceutical and Cosmetics

Why Test?

Artificial light and sunlight can degrade consumer products, especially cosmetics and pharmaceuticals, compromising their efficacy. Even protective packaging can fade from exposure to lighting in stores and at home. Don’t leave it to guesswork—test for durability and quality assurance.

Plastics and Packaging

Why Test?

Some plastic parts are finished products, while others serve as containers for your product. Materials exposed to sunlight, moisture, and heat are vulnerable to the damaging effects of nature, making it essential to design products that can withstand these harsh conditions.

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FAQs

What is the purpose of weathering test?

The purpose of a weathering test is to check how materials perform and last under simulated environmental conditions like sunlight, rain, and temperature changes. It helps predict durability, identify weaknesses, and improve product quality for outdoor use.

What are the causes of weathering?

Weathering is caused by natural factors like sunlight, rain, wind, temperature changes, and biological activity. It can also result from chemical reactions, such as oxidation or acid rain.

What are the three types of weathering?

The three types of weathering are physical, chemical, and biological. Physical weathering breaks materials into smaller pieces without changing their chemical composition, often due to temperature changes, freeze-thaw cycles, or abrasion. Chemical weathering involves chemical reactions, such as oxidation, hydrolysis, or acid rain, that alter the material's composition. Biological weathering occurs when plants, animals, or microorganisms weaken materials, like tree roots growing in cracks or lichens producing acids.

What is the difference between erosion and weathering?

Weathering is the process of breaking down rocks and minerals into smaller pieces. Erosion, on the other hand, involves the movement or transportation of these weathered materials from one place to another. Weathering happens in place, but erosion involves movement by wind, water, or ice.

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