ASTM G155 Testing: Complete Guide to Xenon Arc Weathering Test for UV Resistance and Material Durability
What is ASTM G155 Testing?
ASTM G155 is a standard practice that describes the operating procedures in detail for using a xenon arc light apparatus to expose nonmetallic materials to sunlight, heat, and moisture.
This test method simulates the natural weathering conditions in a controlled laboratory setting to evaluate color change, gloss loss, cracking, chalking, fading, or other degradation phenomena that may occur during outdoor use.
The xenon arc lamp used in this test very closely approximates the full solar spectrum, including UV, visible, and infrared radiation. By controlling variables such as light intensity, temperature, humidity, and water spray, ASTM G155 provides reliable data on material durability, stability, and performance in long-term simulations of sunlight exposure.
Why is ASTM G155 Testing Important?
Exposure to sunlight and environmental factors, such as moisture and temperature fluctuations, can significantly impact the performance and lifespan of materials.
ASTM G155 testing is essential for evaluating and comparing the weathering resistance of nonmetallic materials before they are used in real-world conditions.
ASTM G155 helps to:
- Simulate long-term outdoor exposure in a short testing time.
- Predict material performance and degradation behavior under sunlight.
- Ensure product durability, quality, and reliability in outdoor environments.
- Support product design, material selection, and compliance with industry standards.
- Reduce field failures by identifying weaknesses early in the development process.
This test method is widely recognized across various industries, including automotive, aerospace, construction, coatings, textiles, and plastics manufacturing, where UV stability and color retention are crucial to product performance.
Which Materials Can Be Tested Under ASTM G155?
ASTM G155 applies to a wide variety of nonmetallic and polymer-based materials, including:
- Plastics and polymers (e.g., polyethylene, PVC, polypropylene)
- Paints and coatings
- Textiles and fabrics
- Rubber and elastomers
- Adhesives and sealants
- Composites and laminates
- Automotive interiors, dashboards, and exterior trim components
Specimens can be tested in their finished form or as sheets, films, or molded pieces, depending on the intended end-use.
What Information Do ASTM G155 Test Results Provide?
| Parameter | Unit | Description |
| Color Change (ΔE) | Unitless | Variation in color compared to the unexposed control |
| Gloss Retention | % | Reduction in surface gloss due to UV exposure |
| Cracking/Chalking | Visual rating | Surface deterioration observed during or after exposure |
| Tensile Strength Retention | % | Measure of mechanical property degradation |
| Yellowing Index | Unitless | Degree of discoloration after exposure |
These results reveal how a material visually and mechanically degrades under accelerated sunlight and weathering conditions.
What Industries Use ASTM G155 Testing?
ASTM G155 testing is widely used across industries that require materials to perform reliably in outdoor or high-UV environments, including:
- Automotive – dashboards, seat fabrics, and coatings
- Aerospace – interior panels and window materials
- Building and Construction – roofing, siding, sealants, and coatings
- Plastics and Polymers – packaging, films, and molded components
- Textiles – outdoor fabrics, awnings, and upholstery
- Paints and Coatings – architectural and industrial finishes
- Renewable Energy – solar panels and protective films
This test ensures that materials meet durability and colorfastness standards required for long-term exposure applications.
What Equipment Is Used for ASTM G155 Testing?
The leading equipment used is a xenon arc weathering chamber, which includes:
- Xenon arc light source that replicates full-spectrum sunlight
- Optical filters to control UV and visible wavelength exposure
- Temperature and humidity control systems
- Water spray and condensation systems to simulate rain and dew
- Specimen holders to position samples uniformly
- Monitoring sensors for irradiance, black panel temperature, and relative humidity
How Is the ASTM G155 Test Performed?
Step-by-Step Procedure:
- Sample Preparation:
Specimens are prepared according to specified dimensions and cleaned to remove any surface contaminants that may affect test results. - Apparatus Setup:
The xenon arc chamber is equipped with the appropriate optical filters (e.g., daylight, window glass, or extended UV) based on the exposure conditions required. - Exposure Cycle:
Samples are exposed to controlled cycles of light, temperature, humidity, and water spray to simulate natural weathering. Common cycles include:- Light only (constant illumination)
- Light and moisture (alternating dry and wet periods)
- Monitoring:
Key test parameters such as irradiance, black panel temperature, chamber humidity, and water spray duration are continuously monitored and maintained as per the selected test cycle. - Evaluation:
After the desired exposure duration, samples are visually inspected and tested for color change, gloss retention, mechanical strength, and surface degradation.
What Are the Standard Test Conditions?
| Parameter | Typical Condition |
| Irradiance | 0.35–1.10 W/m² at 340 nm |
| Black Panel Temperature | 63°C ± 3°C |
| Chamber Humidity | 50% ± 10% RH |
| Water Spray Cycle | 18 min every 2 hours (varies by method) |
| Exposure Duration | Up to 1000 hours (or as specified) |
| Filter Type | Daylight or Window Glass filters |
Standardized cycles are outlined in ASTM G155 Table X1, allowing users to select the most relevant exposure type for their material or product application.
Key Properties Measured
ASTM G155 evaluates a material’s resistance to photodegradation and environmental aging.
The key properties assessed include:
- Color stability and fading resistance
- Surface appearance (chalking, cracking, gloss loss)
- Mechanical strength retention
- Optical property changes (transmittance, haze)
- Overall durability and service life prediction
These properties are critical indicators of weathering performance and product longevity in outdoor environments.
Related Testing Methods
Other commonly used standards for weathering and UV exposure testing include:
- ASTM G154: Fluorescent UV lamp exposure of nonmetallic materials
- ISO 4892-2: Xenon arc exposure of plastics
- ASTM D2244: Calculation of color differences from instrumentally measured color coordinates
- ASTM D523: Measurement of gloss on surfaces
- ASTM D4587: UV exposure of coatings using fluorescent UV lamps
These complementary standards allow a comprehensive evaluation of UV stability and environmental resistance.
Conclusion
ASTM G155 provides a standardized method for evaluating the response of nonmetallic materials to exposure to sunlight, heat, and moisture.
By using a xenon arc light source that simulates natural weathering conditions, the following is made possible for manufacturers, researchers, and quality engineers:
- Predict material performance under outdoor use.
- Validate product durability and UV resistance, and
- Supports both product claims and regulatory compliance.
Whether for automotive coatings, construction materials, or outdoor fabrics, ASTM G155 remains the foundational test method for evaluating long-term weathering performance, ensuring product reliability in diverse environmental conditions.
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FAQs on ASTM G155 Testing
What is the purpose of ASTM G155 testing? ASTM G155 testing is conducted to evaluate how nonmetallic materials—such as plastics, coatings, textiles, and composites—respond to long-term exposure to simulated sunlight, heat, and moisture. It helps determine a material’s durability, color stability, and surface integrity under conditions that mimic real outdoor weathering.
What is a xenon arc light apparatus? A xenon arc light apparatus is a laboratory weathering device equipped with a xenon arc lamp that closely replicates the full solar spectrum (ultraviolet, visible, and infrared light). This apparatus provides controlled exposure conditions to test how materials degrade under sunlight and environmental stress.
How long does an ASTM G155 test typically run? The duration varies depending on the exposure conditions and the type of material. Common exposure periods include 500, 1000, or 2000 hours, representing months or years of outdoor exposure. The actual duration is often determined by customer specifications or the end-use requirements of the product.
Can ASTM G155 simulate indoor exposure conditions? Yes. By using Window Glass filters, ASTM G155 can simulate indoor sunlight exposure, such as light passing through glass. This is commonly used for testing automotive interiors, architectural coatings, and indoor furnishings.
