General guidance for Laboratory Light Exposure to Paints and Varnishes
ISO 16474-1 serves as the framework for assessing how paints and varnishes withstand environmental exposure. This standard provides the technical guidance needed to operate laboratory light sources (such as xenon-arc and fluorescent UV lamps) with consistency. Although developed in ISO's paints and varnishes committee, the information is general to weatherability testing, and indeed much of the same content is found in ISO 4892-1, its counterpart in the Plastics committee.
Whether you are benchmarking new formulations or ensuring long-term product reliability, ISO 16474-1 serves as the first step in your testing process.
What Guidance is Referenced in ISO 16474-1
ISO 16474-1 establishes general requirements for exposing materials to laboratory light sources to evaluate their resistance to light, heat, and moisture.
Test Purpose and Use
- Accelerated laboratory weathering exposures are intended to compare relative material durability
- No laboratory test is a complete simulation of real-world exposure
- Results should not be used to assign universal acceleration factors or predict service life, without outdoor data for correlation
- Replicates and control materials are recommended
Laboratory Exposure Devices
- Defines general requirements for producing and controlling laboratory light sources containing UV, visible, and infrared radiation, with reference solar spectra for comparison.
- Outlines requirements for irradiance unformity and specimen repositioning
- Defines black panel and black standard (insulated black panel) thermometers for temperature, as well as optional chamber air temperature control
- Presents options for water delivery including humidification, condensation, water spray, and immersion, plus requirements for water purity.
- References instrument-specific methods defined in:
- ISO 16474-2 (Xenon arc)
- ISO 16474-3 (Fluorescent UV)
Test Specimens
- Test specimens should be prepared using methods that closely reflect real-world manufacturing processes
- Replicates are needed for statistical significance, especially for tests that will undergo destructive testing
- Standardized practices for storage and handling are encouraged to minimize variability between tests
Test Conditions and Procedure
- Establishes tolerances for test parameter measurement at the control point, known as "operational fluctuation."
- Supports both destructive and non-destructive property measurements
- Recommends evaluation intervals based on time or radiant exposure needed to produce a defined change in a material property
- Explains how results are to be reported and used in specifications
Together, these guidelines give a general idea of how accelerated weathering testing can be conducted. Annexes to the document also provide information on measuring uniformity, understanding challenges in developing correlation, and solar reference spectra.
How Q-Lab Can Help
The QUV accelerated weathering test chamber and Q-SUN xenon arc test chamber are fully capable of meeting test methods that reference ISO 16474-1 and the related instrument-specific standards it supports and references. Q-SUN testers are designed to perform testing according to ISO 16474-2 - Paints and varnishes - Methods of exposure to laboratory light sources - Part 2: Xenon-arc lamps, while QUV testers meet the requirements of ISO 16474-3 - Paints and Varnishes - Methods of exposure to laboratory light sources - Part 3: Fluorescent UV lamps.
For organizations exploring accelerated weathering and light stability testing but not yet ready to invest in QUV or Q-SUN equipment, Q-Lab offers comprehensive laboratory exposure testing services in our fully equipped facilities in Florida and Germany.
Q-Lab’s weathering and light stability tests support quality control, material certification, exterior durability studies, and performance predictions. We also serve as an independent third party when objective verification of test results is required. For more details on our accelerated weathering capabilities, please refer to the Q-Lab Testing Services brochure.
More ISO 16474-1 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.
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