Determination of Fogging Properties of GM9305P Automotive Interior Upholstery Materials

The GM9305P standard, developed by the General Motors company, describes a test method for determining the fogging properties of automotive interior upholstery materials.

The test method presented in this standard is applied to determine the fogging tendencies of all interior and ventilation system materials in vehicles. This method is also used for other applications, such as the fogging properties of foam or sealants used with automotive lenses.

This standard defines two alternative tests with different methods to assess the degree of fogging:

• Method A (photometric method). This method evaluates the volatility of organic components by gloss meter measurements.
• Method B (gravimetric method). This method determines the mass of mist condensation on the aluminum foil in mg by weighing the foil before and after the fogging test.

The different beaker volumes used by the various fog test units require a scaling factor to ensure results are comparable from one fog test unit to the next. Scaling factors of fog equipment based on manufacturers are included in the standard annex (Annex A).

Fog is a physical phenomenon that occurs when steam condenses on a cold surface in contact with a humid environment. The saturated vapor pressure depends on the temperature, the air saturated with water cools on the surface of the cold body, for example the glass, and the partial pressure of the water exceeds the saturated vapor pressure, some of the water liquefies and accumulates on the surface as fine droplets.

Consequently, the phenomenon of fogging is a common occurrence inside a vehicle. Moisture trapped in the passenger compartment condenses over time and settles on the windows that cool due to the drop in temperature (usually at night).

Since fogging is an annoying and even dangerous aspect of driving, certain standards and methods make it possible to analyze the mist behavior in the passenger compartment using different polymers.

A standard has been published by the International Standards Organization (ISO) that includes a test method for determining the fogging properties of plastic or rubber-coated textiles used as coating material in the vehicle interior (ISO 6452). The raw materials that make up these materials are also subjected to this test.

Among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors, our organization also provides testing services for the determination of fogging properties of automotive interior flooring materials, within the scope of the GM9305P standard, with its trained and expert staff and advanced technological equipment.