1.1 Four test methods to accelerate the effects of long term indoor illumination on artists' materials are described below. One of the natural daylight methods and one of the xenon-arc methods are used to categorize the lightfastness of colorants.

1.1.1 Test Method AExposure in southern Florida to natural daylight filtered through window glass.

1.1.2 Test Method BExposure in Arizona to natural daylight filtered through window glass.

1.1.3 Test Method CExposure in a non-humidity controlled xenon-arc device simulating daylight filtered through window glass.

1.1.4 Test Method DExposure in a humidity controlled xenon-arc device simulating daylight filtered through window glass.

1.2 These test methods are used to approximate the color change that can be expected over time in colorants used in artists' materials exposed indoors to daylight through window glass. Note 1The color changes that result from accelerated exposure may not duplicate the results of normal indoor exposure in a home, art gallery, or museum. The relative resistance to change, however, can be established so colored materials can be assigned to categories of relative lightfastness.

Users who wish to test colored materials under fluorescent illumination should consult Practice D 4674.

1.3 Lightfastness categories are established to which colorants are assigned based on the color difference between specimens before and after exposure.

1.4 Color difference units are calculated by the CIE 1976 L*a*b* color difference equation.

1.5 These test methods apply to colored artists' materials.

1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

This standard does not purport to address 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.