1.1 This practice covers a method for exposing specimens of colored art materials indoors to sunlight coming through a closed window. A card containing eight Blue Wool References is exposed simultaneously. Blue Wool References 3, 6, and 7, are used as controls in determining when to remove test specimens from exposure and rate them. Test specimens are rated by assigning each specimen the number of the Blue Wool Reference that shows the same amount of color change.

1.2 This practice shall only be used to evaluate the lightfastness of art materials not conforming to specifications D4302, D5098 or D5067 and when it is not feasible to use Test Methods D4303. Practice D5398, which is a simpler method, may be used by artists to evaluate the lightfastness of their own materials.

1.3 This practice is not suitable for evaluating materials with a high oil content such as artists' oil, resin oil or alkyd paints.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.