The standard “VW PV 3929 Non-metallic materials - Dry, hot climate wear (exterior)” developed by the Volkswagen automobile company describes the procedure for testing the ageing behavior (e.g. changes in color and gloss) of plastics, elastomers, glass-based components, convertible fabrics, paints and similar coatings exposed to weathering and sunlight. This test is carried out by artificial abrasion in a dry, hot climate (e.g. Kalahari, South Africa and Arizona).
For certain applications, ageing criteria may consist of changes in mechanical properties or cracking. Therefore, additional tests may be required, along with visual assessment, color measurement and gloss measurement. These tests may include, for example, tensile tests, determination of impact strength, light transmittance, haze, determination of hardness and microscopic examination.
In this procedure, samples are irradiated using xenon arc light. The spectral radiation components of the xenon arc light are adapted to ultraviolet and visible light in the spherical radiation by means of filters. The tests shall be performed in instruments complying with the specifications in “ISO 4892-2 Plastics - Methods of exposure to laboratory light sources - Part 2: Xenon arc lamps” or “ISO 16474-2 Paints and varnishes - Methods of exposure to laboratory light sources - Part 2: Xenon arc lamps”. In each case, the test conditions define a 300-year cycle based on average UV radiation doses (400 nm to 1 nm) in dry, hot climatic regions (e.g. the Kalahari, South Africa and Arizona).
Light exposure devices used in tests must comply with ISO 4892-2 or ISO 16474-2 standards or have been tested by means of comparison tests with existing systems in this standard. To ensure comparable test results between the supplier and the purchaser, the type of device to be used in each specific case should be selected in consultation with the materials development and materials engineering departments.
The weathering conditions should be taken from the table given in the standard. To ensure compliance with the test temperatures, the test devices should be installed in a temperature-stabilized test chamber (18 degrees to 25 degrees) as specified by the manufacturer. The use of flatbed devices is only permitted for testing entire parts or components (e.g. headlights) after agreement with the purchaser's materials development and materials engineering departments.
Samples shall be taken from a representative point on the finished part to be tested or from test panels produced under production conditions with the same surface (e.g. coating, grain, coating structure) and shall be documented by photographs. Samples shall be as flat and of equal thickness as possible. The sampling direction of the reference sample and associated samples shall be marked in a weatherproof manner (e.g. by cutting a notch on the side of the sample considered to be the top). For coated samples, the coating thickness shall be determined and documented.
The sample is gently cleaned under warm running water using only wet hands. A mild laboratory detergent that does not leave oily residue can be used as a cleaning agent. The surfaces to be tested should not be damaged by cleaning. The samples are rinsed with clean water and dried by blowing with oil-free compressed air. The sample surface should be kept free of fingerprints throughout the test period.
The specimen size must match the maximum clampable test surfaces on the original specimen carriers.
The end point of the weathering cycle is achieved after a test time/irradiation dose specified in the table. To ensure a uniform irradiation intensity, it must be checked and corrected regularly with a measuring device suitable for this purpose. The irradiation device must be calibrated with a radiometer according to the manufacturer's specifications.
Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "VW PV 3929 Non-metallic materials - Wear in dry, hot climates (external)" standard are also provided to businesses.
To get an appointment, to get more detailed information or to request an evaluation, you can ask us to fill in our form and reach you.
