Weathering Testi — ISO 877 / ASTM G7 / ISO 4892

What Is Weathering?

Weathering testing is a test group that assesses a material's ageing under the combined effects of sun, heat, humidity and pollutants. It is conducted naturally (outdoor) or in accelerated form (laboratory).

Purpose of Weathering

The purpose is to determine how long a material intended for outdoor use retains its appearance and mechanical properties.

Which Products Is Weathering Applied To?

Building profiles and facade elements
Automotive exterior parts
Paint and coating systems
Garden furniture and outdoor plastics
Membranes and roofing

In Which Sectors Is Weathering Used?

ElectronicsElectricalAutomotiveDefenceAerospace

Standards Related to Weathering

ISO 877
ASTM G7
ASTM G24
ISO 4892-2
ISO 4892-3
ASTM G155Accelerated aging with xenon arc test
ASTM G154fluorescent UV accelerated aging test

Weathering Conditions

Method: Natural outdoor exposure or laboratory accelerated aging
natural exposure: Panel angle, orientation and climate zone are defined in the standard
Accelerated: Xenon arc or fluorescent UV cycles
Time: Years of natural exposure; Hundreds to thousands of hours in time-lapse

Equipment for Weathering

Outdoor exposure racks (natural method)
Xenon arc or fluorescent UV chamber
Colour, gloss and mechanical measurement instruments
Meteorological data logging (natural method)

Sample Requirements for Weathering

Initial colour, gloss and mechanical values must be measured
A reference sample must be kept in the dark
Panel angle and orientation must be recorded for natural exposure
Generally at least three specimens

Duration of Weathering

One to five years for natural exposure; weeks to months for accelerated methods, depending on the specification.

Weathering Procedure

1Initial measurements are taken and a reference sample is kept.
2A method is selected: natural exposure or accelerated cycling.
3Samples are placed at the defined angle and location.
4Interim measurements are taken at defined intervals.
5At the end of the exposure, colour difference, gloss and mechanical properties are compared.

Weathering Acceptance Criteria

The acceptance criterion is given in the specification as maximum colour difference, maximum gloss loss, or minimum retained mechanical property.

Evaluation of Results

Accelerated results do not translate directly to natural exposure; correlation can only be established with coefficients validated for the same material class. The method must therefore always be stated in the report.

Weathering Report

Standard and method applied
Exposure conditions or cycle programme
Total duration or irradiance
Colour, gloss and mechanical results
Reference sample comparison

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Construction and automotive material specifications

Environmental and Climatic Testing — What Does This Testing Field Cover?

The section below describes the field that the Weathering test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Environmental testing shows whether a product withstands ambient factors such as temperature, humidity, pressure, solar radiation, dust, water and corrosive atmospheres. The aim is not to break the product but to bring forward, in ACCELERATED form, the conditions it will meet over its life.

Test profiles are derived from the product's real exposure, and that derivation is the actual engineering work of the field. A device operating in an enclosed office and one mounted on a pole are not tested with the same profile. The IEC 60068 series defines general methods, MIL-STD-810 military profiles, RTCA DO-160 aviation profiles and the ISO 16750 series location-based automotive profiles. A test applied without a profile selection produces both unnecessary cost and false confidence.

Temperature tests simulate three separate phenomena and all three produce different failure modes. Steady high/low temperature tests whether the material can operate at that temperature. Temperature CYCLING creates fatigue at joints between materials with different expansion coefficients — solder cracks appear here. Thermal SHOCK intensifies this effect through an abrupt transition.

There is a distinction in humidity testing too. Steady damp heat shows the diffusion of moisture into the material and its effect on insulation properties. Cyclic damp heat creates condensation: water droplets form on the cooling surface, and this is far more aggressive than dry humidity. Water ingress into enclosures, increased leakage current and corrosion usually appear in the cyclic test.

Dust and water protection is a separate body of work and is expressed by the IP code. The point to note here is that an IP test is not a DURABILITY test: it shows that protection is provided under defined and short-duration conditions, not resistance to long-term immersion or pressure washing.

The most common mistake in this family is translating a test result directly into a LIFE PREDICTION. Accelerated tests are designed for comparison and design verification; a reliable conversion between hours in a chamber and years in the field can only be established with a material-specific acceleration model calibrated against field data.

Functional monitoring determines the value of the test. Keeping a product in a temperature chamber and then switching it on does not show what happened DURING the test. In critical applications the product is operated throughout the test and its parameters are monitored; intermittent faults that appear and disappear can only be caught this way.

Method groups in this field

Temperature
Dry heat, cold, change of temperature and thermal shock; steady and cyclic profiles.
Humidity
Steady damp heat and cyclic damp heat; cycles with condensation are more aggressive.
Water and dust
IP protection tests: dripping, spraying, jets, immersion and dust tightness.
Radiation and ageing
Accelerated ageing by xenon arc and fluorescent UV, solar radiation simulation.
Pressure and altitude
Low pressure (altitude) and rapid pressure change tests.
Corrosive atmosphere
Salt spray, mixed flowing gas corrosion (simulating industrial atmospheres), mould and fungus tests.

Commonly confused in this field

Test duration cannot be converted into field life; a conversion made without an acceleration model is misleading.
Temperature cycling and steady temperature produce different failure modes; neither replaces the other.
If the product is not operated during the test, intermittent faults remain invisible; functional monitoring determines the value of the test.
IP protection is not evidence of durability; it shows protection under defined and short-duration conditions.
A test applied without profile selection both increases cost and gives false confidence.
The mounting and orientation arrangement affects the result; the report must document it.

Which decisions these results support

Design verification and qualification
Declaration of the protection class and operating temperature range
Reproducing field failures in the laboratory and root cause analysis
Supplier component approval
Decisions on warranty period and storage conditions

Related Tests

Frequently Asked Questions About Weathering

How many years of natural exposure does an accelerated test correspond to?

There is no universal conversion factor. Correlation depends on the material class, degradation mechanism and climate zone. Specifications therefore usually define test duration or total irradiance directly.