ASTM D904 - Standard Practice for Exposure of Adhesive Specimens to Artificial Light :
ASTM D904 is a standard developed to evaluate the effects of ultraviolet (UV) light on adhesive bonded joints. This practice provides data for comparing the relative durability of different adhesives under controlled UV exposure conditions. It is important to note that this method does not aim to predict the service life of an adhesive bond, but rather to establish a relative comparison of adhesive durability.
The practice takes into account various factors that can significantly influence test results. One factor is the type of light source used (xenon-arc or fluorescent UV), which can lead to variations in results due to their different spectral-irradiance profiles. Therefore, the performance of adhesives under different light sources should not be compared.
Other factors include variations in the operating conditions of the testing method, the type and UV transmittance characteristics of the transparent adherend, and differences between exposure instruments from different manufacturers. For accurate comparisons, materials must be tested simultaneously in the same instrument and under the same conditions.
The scope of ASTM D904 practice includes principles and procedures for UV light aging of adhesive bonded joints. It applies to joints with at least one glass or transparent adherend, using either fluorescent UV (Method A) or xenon-arc light sources (Method B). The practice strictly pertains to the exposure procedures and apparatus for obtaining, measuring, and controlling aging conditions. Other aspects such as sample preparation, strength, test conditions, and results evaluation are covered by other relevant ASTM test methods or specifications.
It is also worth mentioning that this practice does not determine the effects of atmospheric pollutants, biological organisms, salt, or freeze/thaw cycles on adhesives.