Image above: The blue white-balance paper included in the Infragram filter kit after exposure to sunlight. The "shadow" of the little clip is the only area without much fading. That much fading happened in two to three hours.
There was intense sunlight on LEAFFEST Sunday when we finished the test photos with the web cam board. In the hour or so that the set of calibration cards was in the sun, the blue paper faded noticeably. Today I confirmed that the blue fades quickly by placing a sensor assembly on the card in the hazy sun for an hour or two.
So if you have an Infragram filter kit, you might want to protect that blue paper from long term exposure to bright light. However, even if the paper fades, it is still useful for white balancing an Infragram camera. In fact, the color of the light hitting the paper during the white balancing process may be just as important as the color of the paper.