ASTM D4303-99

1.1 Three test methods consisting of exposure to light (natural sunlight or simulated sunlight) filtered through glass are described as follows:

1.1.1 Test Method A -Exposure under glass to the sun,

1.1.2 Test Method B -Exposure to irradiance from artificial daylight fluorescent lamps, and

1.1.3 Test Method C -Exposure in xenon-arc lightfastness apparatus.

1.2 These test methods are used to approximate the color change that can be expected over time in pigments used in artists' paints in normal indoor exposure.

Note 1-The color changes that result from accelerated exposure may not duplicate the results of normal indoor exposure in a home or gallery. The relative resistance to change, however, can be established so pigments can be assigned to categories of relative lightfastness.

1.3 Lightfastness categories are established to which pigments 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 artists' oil, resin-oil, acrylic emulsion, alkyd, and watercolor paints.

1.6 This standard does not purport to address the safety problems, 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.