Lightfastness of printed ink jet media for specified periods of time is pertinent to the end use of these materials. Since the ability of an ink jet print 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 the effect of accelerated testing 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 office lighting where overhead fluorescent light and window-filtered daylight is used for illumination by simulating these conditions.

The accelerated procedure covered in this practice is intended to provide a means for the rapid evaluation of the effect of light under laboratory conditions. Test results are useful for specification acceptance between producer and user, for quality control, and for research and product development.

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