ASTM G90-23 PDF

Full title and description

ASTM G90-23 — Standard Practice for Performing Accelerated Outdoor Weathering of Materials Using Concentrated Natural Sunlight. This practice describes procedures, apparatus, and controls for accelerated outdoor exposure testing of materials using linear Fresnel reflector concentrators that concentrate natural sunlight to accelerate weathering (irradiance, heat, and moisture) and to provide repeatable, comparative durability data.

Abstract

G90-23 specifies a standardized method for performing accelerated outdoor weathering of materials by concentrating natural sunlight with linear Fresnel reflector devices. It defines apparatus configuration, specimen mounting and size limits, measurement and control of irradiance and environmental conditions, maintenance of the exposure machine, and test execution guidelines intended to produce repeatable comparative results. The practice emphasizes use of control specimens, replication, and caution when extrapolating acceleration factors to natural weathering.

General information

• Status: Active (current edition G90-23).
• Publication date: Approved July 1, 2023; published (ASTM book release) August 2023.
• Publisher: ASTM International.
• ICS / categories: 19.040 — Environmental testing (Weathering and durability).
• Edition / version: G90-23 (2023 edition).
• Number of pages: 14.

Scope

This practice covers procedures for accelerated outdoor exposure testing of materials using linear Fresnel reflector concentrators that use the sun as the source of irradiance. It defines apparatus features, sample mounting and dimensions (applies to specimens that fit the target board; not recommended for specimens exceeding 13 mm / 1/2 in. thickness for many machines), measurement and control of irradiance, temperature and moisture conditions, and maintenance procedures for the concentrator and mirrors. The practice does not prescribe specific exposure conditions for particular materials; rather it standardizes the method for obtaining, measuring, and controlling conditions during concentrated-sunlight accelerated tests so results can be reproducible and comparable.

Key topics and requirements

• Apparatus description and configuration: linear Fresnel reflector concentrator, tracking, target board, mirror maintenance and cleanliness.
• Irradiance measurement and control: procedures for measuring concentrated direct normal irradiance and maintaining setpoint levels during exposure.
• Specimen mounting and geometry: standard target-board dimensions, mounting fixtures, orientation and spacing to ensure consistent exposure.
• Specimen limitations: guidance on specimen thickness (generally not recommended above ~13 mm / 1/2 in. for many machines) and size to ensure adequate cooling and representative exposure.
• Environmental monitoring: temperature, humidity, wetting cycles and other conditions to be recorded and controlled where applicable.
• Test execution: use of control specimens, recommended replication (at least three replicates), and statistical treatment guidance for comparative testing.
• Maintenance and calibration: mirror/reflector maintenance, periodic calibration of radiometric instruments, and recommended referenced calibration methods.
• Limitations and interpretation: warnings about material-specific acceleration factors, location-dependence of correlations to natural weathering, and that the practice is intended for comparative—not absolute—determinations unless validated by correlation.

Typical use and users

Used by materials scientists, coatings and polymer developers, test laboratories, quality assurance teams, OEMs, and researchers assessing comparative weathering performance of materials and coatings. Typical applications include accelerated screening of formulations, comparative durability ranking, research into degradation mechanisms under high-irradiance exposures, and supporting product development decisions where concentrated-sunlight exposures are informative.

Related standards

Related ASTM practices and test methods frequently used with or referenced by G90 include: ASTM G130 (radiometric calibration / related radiometry methods), ASTM D4364 and D4141 (concentrated-sunlight and solar box exposure practices), ASTM D1435 and D1014 (outdoor/plastics and coatings exposure practices), ASTM D5722 (related accelerated outdoor weathering procedures), and other G03 committee standards such as G201 (outdoor glass-covered exposure apparatus) and G179 (temperature devices for natural weathering). Users should consult referenced standards in the G90 text for instrument calibration, radiometry, and evaluation methods.

Keywords

accelerated outdoor weathering, concentrated natural sunlight, Fresnel reflector, linear Fresnel concentrator, irradiance, weathering, durability, exposure apparatus, radiometry, specimen mounting, environmental testing.

FAQ

Q: What is this standard?

A: ASTM G90-23 is a standard practice that specifies how to perform accelerated outdoor weathering tests using linear Fresnel reflector concentrators that concentrate natural sunlight to accelerate the exposure of materials.

Q: What does it cover?

A: It covers apparatus configuration, procedures for mounting specimens, limits on specimen size and thickness, measurement and control of irradiance and environmental conditions, maintenance of the exposure machine and mirrors, requirements for controls and replication, and guidance on interpreting accelerated results relative to natural weathering.

Q: Who typically uses it?

A: Test laboratories, materials and coatings developers, academic and industrial researchers, and quality/verification teams that need comparative accelerated outdoor weathering data using concentrated natural sunlight.

Q: Is it current or superseded?

A: G90-23 is the current edition (2023). It replaces earlier editions (for example G90-17 and prior versions) and is active as the authoritative practice from ASTM International.

Q: Is it part of a series?

A: Yes — G90 is part of the ASTM G03 Committee suite of weathering and durability standards (Subcommittee G03.02). It is commonly used alongside related G03 and D-series outdoor exposure and radiometry standards for a complete weathering test program.

Q: What are the key keywords?

A: Concentrated sunlight, Fresnel reflector, accelerated weathering, irradiance control, specimen mounting, durability, environmental testing.