Welcome to Net54baseball.com. These forums are devoted to both Pre- and Post- war baseball cards and vintage memorabilia, as well as other sports. There is a separate section for Buying, Selling and Trading - the B/S/T area!! If you write anything concerning a person or company your full name needs to be in your post or obtainable from it. . Contact the moderator at leon@net54baseball.com should you have any questions or concerns. When you click on links to eBay on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network. Enjoy!
In most cases, it is easy to determine if a card has been sun-faded to create a "white letter" version. With the green backgrounds, the green will appear blue (as seen below). The brown backgrounds will appear more purple.
The 10 or so red background cards may be tougher to tell as red is a primary color, but red does typically fade faster than blue but not as quick as yellow. While I have not seen a faded red version (yet, in my west facing window now),
my speculation is that the red background will have a dull/faded appearance.
I would not let the possibility of sun fading deter you, just apply common sense/caution when considering any of these WL cards.