The colourfastness to light of the specimen is evaluated by comparison of the colour change of the exposed portion to the masked control portion of the test specimen or unexposed original material, using BS1006 AO1 Grey scale for colour change or by instrumental colour measurement. Lightfastness classification is accomplished by evaluation versus a simultaneously exposed series of Blue Wool Lightfastness Standards.

Здесь описывается процедура тестирования цветостойкости.