Understand Your Application's Durability with ISO 16474-3
ISO 16474-3:2021 specifies methods for testing paints and varnishes under fluorescent UV lamps to simulate weathering from daylight or window-filtered light. It covers UV exposure, heat, and moisture conditions, detailing the test apparatus, specimen preparation, setup, and performance of test cycles for assessing coating durability. This internationally-recognized, performance-based testing method is ideal for coatings industry professionals ensuring product performance.
Test Parameters
ISO 16474-3 includes a variety of different test cycles that vary in lamp type, irradiance level, temperature, and water delivery, allowing users to customize their cycle based on their testing goals, materials, and service environments.
Method A: UVA-340 lamps
UVA-340 and UVA-340+ lamps provide the most realistic simulation of the shortwave portion of natural outdoor sunlight. ISO 16474-3 features two cycles that use UVA-340 lamps.
- Cycle 1:
- Exposure period: 4 hour Light, 4 hour Condensation
- Irradiance: 0.83 W/m2/nm @ 340 nm
- Black panel temperature: 60 °C (Light); 50 °C (Condensation)
- Cycle 2:
- Exposure period: 5 hour Light, 1 hour Water Spray
- Irradiance: 0.83 W/m2/nm @ 340 nm
- Black panel temperature: 50 °C (Light); not controlled during Spray
Method B: UVA-351 lamps
UVA-351 lamps simulate shortwave UV from sunlight passing through window glass, and can be used for materials in indoor environments. ISO 4892-3 has one cycle that uses UVA-351 lamps.
- Cycle 3:
- Exposure period: Continuous Light (no moisture)
- Irradiance: 0.76 W/m2/nm @ 340 nm
- Black panel temperature: 50 °C
Method C: UVB-313 lamps
UVB-313EL and UVB-313EL+lamps deliver irradiance at wavelengths even shorter than those experienced on Earth's surface. This can accelerate degradation, making them good for quality control purposes, but can also produce failure modes not observed in real life.
- Cycle 4:
- Exposure period: 4 hour Light, 4 hour condensation
- Irradiance: 0.71 W/m2/nm @ 340 nm
- Black panel temperature: 60°C (Light); 50 °C (Condensation)
- Cycle 5:
- Exposure period: 5 hour Light, 1 hour Water Spray
- Irradiance: 0.71 W/m2/nm @ 310 nm
- Black panel temperature: 60°C (Light); not controlled in Spray step
Q-Lab customers can log in to their Q-Portal account for in-depth information regarding programming and setup for ISO 16474-3.
Why Test to ISO 16474-3
Testing to ISO 16474-3 ensures paints and varnishes are designed to withstand UV, heat, and moisture, simulating real-world weathering. This test method helps manufacturers predict how coatings will withstand exposure to daylight or window-filtered light, preventing premature degradation, fading, or failure in various applications like construction, automotive, and industrial products.
By adhering to these standardized methods, businesses can validate product quality, meet regulatory and customer requirements, reduce costly failures, and enhance reliability, ultimately ensuring longer-lasting and safer coated surfaces.
Pros and Cons of ISO 16474-3
- Great for comparative testing of materials for UV degradation
- The test methods used in ISO 16474-3 often provide strong correlation with material failures experienced in natural outdoor environments
- Use of hot condensation
- ISO 16474-3 delivers continuously reforming condensation at elevated temperatures, providing the most realistic way to accelerate moisture attack
- Variety of lamps defined in test cycles to meet individual testing needs
- Depending on the material or application you are testing, ISO 16474-3 recommends test conditions using various lamp types to meet your particular test goals
- Realism of testing
- The added shortwave of UVB lamps in Method C can reduce test times, but also may cause some polymers to degrade differently than they would outdoors
- The lack of full-spectrum sunlight, as with any UV fluorescent testing, may not reproduce all color change effects
- Excess water spray
- Water spray periods of up to 1 hour are longer than necessary for thermal shock effects, and less effective than hot condensation
How Q-Lab Can Help
QUV Accelerated Weathering Tester
Q-Lab’s QUV accelerated weathering testers fully comply with ISO 16474-3. It is the simplest, most reliable, and easiest-to-use weathering tester available. With thousands of testers in use worldwide, it is the world's most widely-used weathering tester.
Testing Services
If a new tester is not part of the budget, we offer contract testing at either of our two accelerated testing laboratories – Florida or Germany. Both labs are ISO 17025 accredited to perform ISO 16474-3, using the very same QUV test chambers built at our manufacturing plant. In addition to accredited testing, our laboratories are qualified to perform a suite of different evaluations, including color change, gloss retention, tensile hardness, and much more.
Q-PANEL Standard Test Substrates
Q‑PANEL paint test substrates are the world’s most recognizable and widely-used standard test panels, featuring our trademark Q-shaped hole. Q‑Lab manufactures millions of panels each year for a variety of industries, most available immediately from stock.
More ISO 16474-3 Resources
Standards Tool
Review setup and performance information on key international and OEM test standards from ASTM, ISO, SAE, JIS, GB, and more.
Document Library
Browse Q-Lab’s extensive library of weathering testing literature and technical content.
Contact Q-Lab
Ready to get your testing journey started? Our team is here and ready to help.