This test method is intended for detecting and assessing colored textiles which change in color after brief exposure to light but which return to their original shade when stored in the dark. 2. Principle 2.1 A specimen is exposed to light of high intensity for a time much shorter than that necessary to cause permanent change. The change in color of the specimen is assessed immediately after exposure with the Gray Scale for Color Change. The specimen is then stored in the dark under specified conditions and assessed again.