Fogging Characteristics of Interior Automotive Materials

Fogging tests are crucial in evaluating the performance of plastic or elastomeric materials used in automotive or other vehicle interiors. These tests measure the tendency of a material to volatilize substances that can condense and collect on other surfaces, leaving a light scattering film or depositing foreign material. Two methods are used to evaluate this likelihood, namely the photometric and gravimetric methods.

The photometric method evaluates a material's tendency to leave a light scattering film on a glass surface. The test sample is placed in a sealed beaker, and the inside surface of the cooled beaker cover is made of glass. The beaker is then placed in a controlled temperature oil bath for a specific period, usually 3 hours. Gloss readings of the glass cover before the test and after conditioning following the test are then compared, and a fog number is calculated from the glossmeter readings.

The gravimetric method, on the other hand, evaluates a material's tendency to deposit foreign material onto an aluminum foil surface. Similar to the photometric method, the test sample is placed in a sealed beaker, but the inside surface of the cooled beaker cover is made of aluminum foil. The beaker is placed in a controlled temperature oil bath for a longer period of time, usually 16 hours. Weights of the test sample and the aluminum foil before the test and immediately after the test are compared, and the weight loss of the test sample and fog deposit are determined.

To perform these tests, an 80 mm diameter disk of the material being evaluated is required. These tests are critical in evaluating the likelihood of a material to leave a light scattering film or deposit foreign material onto other surfaces in a vehicle's interior. By conducting these tests, manufacturers can determine whether a material is suitable for use in their products.

In summary, fogging tests are critical in evaluating the performance of plastic or elastomeric materials used in automotive or other vehicle interiors. The photometric and gravimetric methods provide valuable information about a material's tendency to leave a light scattering film or deposit foreign material. The tests require an 80 mm diameter disk of the material being evaluated, and the results help manufacturers determine whether a material is suitable for use in their products.