AATCC EP9-2021 Evaluation Procedure for Visual Assessment of Color Difference of Textiles.
6. Test Specimens
6.1 Prior to comparison, all color standards and test specimens shall be conditioned to avoid differences, which may be caused by temperature and humidity (see 10.7).
6.2 Recommended specimen sizes noted below are to be used only if the test method being used does not include specimen size requirements (see 10.6).
6.3 Dyed woven or knitted cloths. The test specimen shall be a representative rectangle of cloth, a minimum dimension of 100 mm in the lengthwise direction by 200 mm wide, whenever possible. Multi- colored specimens shall be of size to incorporate all colors in the pattern. All surfaces shall be clean and free from stains or soiling. Remove torn edges, markings, or other marks from the specimen. Speci- mens shall be cut at least 150 mm from the selvage, and seam areas shall be avoided.
6.4 Narrow cloths, braids, tapes, webbings. The test specimen shall be a minimum of 200 mm in length and full width, as received.
6.5 Loose fiber. The test specimen shall be carded and made into a suitable size lap or pad.
6.6 Threads and yarns. The test specimen shall be in skein form, wound on a card to form a compact area of parallel yarns, or knitted to suitable size. Card windings shall be of sufficient thickness to conceal the card. The card shall not be bowed by tension of the wound yarns.
7. Procedures
7.1 The lighting conditions at the specimen plane shall be tested using instrumentation for assessing light intensity and color temperature to ensure compliance with the specification in 5.1 above. In addition, the user shall test the viewing area for illumination uniformity. The intensity of illumination shall not deviate more than 25% from the center to the viewing edges of the specimen.
7.1.1 The illuminant simulator shall be tested four times per year, or as recommended by the equipment manufacturer (see 10.4).
7.2 Different color difference evalua- tion procedures, as listed below under 7.2.1 and 7.2.2, may be required for dif- ferent applications. Each of these procedures may be used with apparatus from Options A, B or C. Observers shall allow their vision to become adapted to the lighting conditions for at least 2 min prior to making an evaluation. This requirement shall apply again if the lighting con- ditions are changed; i.e., use of another source.AATCC EP9 pdf download.