These test methods are used to determine surface changes following processing, after-treatment, light aging, weathering and temperature aging. The difference in color between a sample that has been exposed to light and the unexposed one is compared with the gray scale sections.
The light-exposed sample is given the number closest to the genuine number on the gray scale. Assigning a color fastness number is an optical test and depends on the subjective color sensitivity of the person carrying out the test. For this reason the TTC has developed a new testing device consisting of a PC with video analysis to eliminate the subjective influence. In addition to the assessment levels of the tested materials, the test record contains a sample card that depicts the successive stages in the aging process.
