LU-8026 - Lab Spectra vs. Sunlight Through Auto Glass

Sunlight is an important cause of damage to materials exposed outdoors. The shorter the wavelength of sunlight, the greater the damage. The shortest wavelengths in sunlight are the ultraviolet. Although ultraviolet light makes up only about 5% of the total solar energy that falls on the earth’s surface, it causes almost all of the damage to durable materials exposed outdoors 1.

Glass acts like a filter on sunlight. It is essentially transparent to visible light, but filters out much of the ultraviolet. Automotive glass is a more efficient filter than ordinary window glass and consequently filters out even more of the damaging UV. However, UV light remains an important cause of damage to interior automotive materials.

Deterioration from sunlight is only one aspect of weathering. For many materials, moisture and temperature may be of even greater importance. No single device can reproduce all of the variables found in different environments. Consequently, any choice of test parameters is somewhat arbitrary. Accelerated test results are always relative. Even the most elaborate weathering tester should be viewed as a screening device.

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