In summary, there are three main ways of rating:
① Color change rating, the sample after the test is evaluated according to the color change gray card;
② Color staining rating, the light-colored sample, lining or solution after the test is evaluated according to the color staining gray card with the original sample (blank lining, original solution);
③ Lightfastness rating, taking the national standard method 3 as an example, the color change degree of the sample after sun exposure is compared with the color change degree of the blue wool standard sample. The American standard is to evaluate the sample after sun exposure and the original sample according to the color change gray card.
Rating work is a display of the results of color fastness testing and is the last step of color fastness testing. No matter how accurate and standardized the previous process is, if there is an error in the rating, all the efforts of the former will be wasted. The consistency of vision is particularly important. In a small range, it is necessary to ensure the consistency of vision of each person in the laboratory, and in a large range, it is also necessary to ensure the consistency of vision between various testing institutions. Only through continuous comparison of personnel and comparison between institutions can the stability of color fastness rating be guaranteed at all times.
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