An example of exposure to light:
http://www.ebay.com/itm/1933-GOUDEY-...item336da3a8ee
Of course this card was tacked to a wall and most likely exposed to direct sunlight, but over time without taking some preventative measures my guess is that you will have some fading due to light exposure. By the way, the strip of red at the bottom of the card in the link is what the card's background should look like.
Just trying to scare you a little.
Brian