Automotive Interior Materials (AIM) box testing with ASTM G201
ASTM G201 is an internationally-recognized test method for conducting outdoor weathering tests using glass-covered enclosures with air circulation, otherwise known as Automotive Interior Materials (AIM) box testing. AIM box testing is a natural, accelerated way to simulate weathering stresses encountered by components behind glass. Q-Lab has a long history with this type of testing - the equipment at Q-Lab Arizona Desert testing is the original design that lead to the development of this international standard. Q-Lab Florida and Arizona Desert Testing both feature extensive capacity to perform these tests, making our team the leader in AIM box testing worldwide.
Key Test Parameters
Glass Type
ASTM G201 specifies two glass types for outdoor weathering tests in glass-covered enclosures:
- Clear tempered glass (non-laminated, 3–4 mm thick)
- Clear laminated glass (6.3 mm with a 0.76 mm PVB layer, ideal for automotive applications)
Other glass types can be used for this testing, if necessary. Additional pieces of these other types of glass would be necessary to measure radiation, or radiation can be measured from within the AIM Box. In all cases, the glass must be cleaned monthly to remove dust and debris, maintaining optimal transparency for solar radiation testing.
Circulating Fan Operation
ASTM G201 outlines two fan operation modes for outdoor weathering tests. The fan directs air between specimens and the glass cover to maintain the desired temperature for consistent exposure conditions.
- Continuous, running during daylight hours (sunrise to sunset). This methodology is very rarely employed because variability in specimen temperatures throughout the year greatly reduces repeatability.
- Temperature-controlled, activating when the black panel temperature (BPT) hits a set limit and turning off at 3 °C below it. This reduces seasonal temperature variability in these tests, providing a high degree of stable temperatures.
Temperature
The standard specifies setting the insulated black panel temperature (BPT) to trigger fan activation at designated limits (85 °C, 93 °C, or 102 °C), with over-temperature protection included to safeguard specimens from damage.
Enclosure Orientation
The test method offers flexible enclosure orientation options for outdoor weathering tests:
- Fixed Tilt Static (typically 5–45° facing the equator) - AIM boxes in South Florida are fixed at 45° South
- Fixed Tilt Tracking (51° tilt with azimuth or full azimuth/elevation to follow the sun) - AIM boxes at Q-Lab Arizona Desert Testing are tracking
- Dual-Axis Tracking TRUE AIM boxes at Q-Lab Arizona Desert Testing are optionally capable of running with mirrors, to further amplify radiant dosage
Custom orientations are also allowed, including non-equator-facing setups, as agreed upon by stakeholders.
Specimen Mounting
ASTM G201 requires specimens to be mounted parallel to the glass cover, 75 mm away for flat specimens, with custom mounting for irregular shapes ensuring key surfaces maintain the same distance. Specimens must also be positioned at least twice the glass-specimen distance from edges, to minimize shadowing.
Exposure Duration
ASTM G201 defines exposure duration for outdoor weathering tests based on any of a number of factors:
- Solar radiant exposure - specified dose for total or specific wavelength bands
- Temperature-normalized radiant exposure - this calculation combines temperature and radiation to account for seasonal temperature variance, especially on Fixed Tilt Tracking tests.
- Predefined property change in materials - color, gloss, strength loss, or others
- Fixed time period - days or even months
Other mutually agreed-upon environmental parameters can be used as well.
Black Panel Thermometer
ASTM G201 specifies using either an automotive black panel (0.60 mm steel, painted black) or ASTM G179-compliant black panel thermometer. Insulated Black Panel Thermometers are most commonly utilized, but Black Panel Thermometers are also allowed. The black panels are placed parallel to the glass cover near the top, at least 200 mm from side edges, with black panel temperature measured every 10 seconds and recorded every 5 minutes for temperature-normalized radiant exposure (TNR) calculations.
Climatological Measurements
ASTM G201 requires measuring solar radiation with a pyranometer for total or specific wavelengths per ASTM G183, with optional daily recording of ambient temperature, relative humidity, and cabinet conditions. Under-glass measurements use a pyranometer/UV-radiometer positioned 75 mm below the glass, aligned with the enclosure’s orientation.
Why Test to ASTM G201
ASTM G201 is an accelerated outdoor test, meaning it combines the realism of natural sunlight with the shortened exposure times of laboratory testing. Automotive companies and suppliers can benefit greatly from the speed and realism of AIM box testing described in this standard.
ASTM G201 tests material durability under controlled outdoor weathering conditions, simulating real-world exposure to glass-filtered sunlight, heat, and humidity—ideal for testing product longevity. Its customizable parameters, including glass type, fan operation, and temperature control, deliver precise, reproducible results, making it a valuable practice for industries like automotive (testing interior trims), construction (evaluating indoor finishes), plastics, coatings, textiles, aerospace, and consumer goods.
Pros and Cons of ASTM G201
- Testing in real-world conditions
- By exposing test specimens to actual sunlight and enclosed temperature fluctuations, ASTM G201 provides realistic conditions
- Customizable test conditions
- ASTM G201 allows users to customize the parameters of the test, including temperature, glass type, and solar tracking
- Cost effective
- AIM box testing is very affordable and a great place to start an interior materials test program
- Material limitations
- The specific design of AIM box testing makes it unsuitable for materials that experience outdoor daylight and moisture
- Duration of specimen exposure
- While testing your specimens in natural environments provides the most accurate results, it requires a significant amount of time in comparison to laboratory testing
- However, outdoor testing in benchmark locations can, in many cases, begin to provide valuable rank-ordered data in a matter of months
Q-Lab's Natural Outdoor Weathering Test Facilities
Q-Lab offers outdoor exposure testing programs at our internationally-recognized, ISO 17025-accredited benchmark locations in Florida and Arizona. Weathering exposures at these sites are not only realistic; they also could be considered a form of accelerated weathering testing (depending on where the product will be used outdoors) and are the best way to verify laboratory test results. Q-Lab also provides all users with climate data to enhance interpretation of data collected during outdoor exposures. See our Outdoor Testing brochure for more information on these sites and our Testing Services brochure to learn about our full range of weathering testing services.
Natural Outdoor Testing Services Resources
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