6.1.3 Color Change
As used in lightfastness testing, a change in color of any kind (whether a change in hue, saturation, or lightness) discernible by comparing the exposed area of the specimen with the masked area, when viewed in north skylight or equivalent source with illumination of 538 lux (50 foot candles) or more on the surfaces.4 For example, under the collar or lapel and inside seams or hems.**
