5.1 Lightfastness of printed ink jet media for specified periods of time is pertinent to the end use of these materials. Since the ability of ink jet prints to withstand color changes is a function of the spectral power distribution of the light source to which it is exposed, it is important that lightfastness be assessed under the conditions appropriate to the end use application. While ink jet prints may be handled and displayed under a variety of conditions, this practice is intended to produce the color changes that may occur in ink jet prints upon exposure to irradiation from daylight filtered through window glass by simulating these conditions.

5.2 The accelerated procedure covered in this practice is intended to provide a means for the rapid evaluation of relative lightfastness under laboratory test conditions. The Practice does not provide a rating of the lightfastness of the prints, but determines the lightfastness ranking of a series of prints or the performance compared to controls with known lightfastness. Test results are useful for specification acceptance between producer and user, for quality control, and for research and product development.

5.3 Color changes may not be a linear function of duration of exposure. The preferred method of determining effect of the light is to expose the prints for a number of intervals and to assess the exposure time required to obtain a specific color change or change in optical density.

1.1 This practice covers specific procedures and test conditions that are applicable for xenon-arc exposure of ink jet media prints conducted in accordance with Practices G151 and G155 . The laboratory accelerated procedure is intended to determine the relative lightfastness of ink jet prints in office environments where window filtered daylight is used for illumination.

1.2 The two criteria used to determine relative lightfastness are instrumental color change and change in optical density.

1.3 This practice is useful in determining the relative lightfastness of a series of prints or the relation of the lightfastness of the print of interest to the performance of controls with known lightfastness exposed simultaneously.

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. Specific precautionary statements are given in section 8 .

1.5 There is no equivalent ISO standard.