Pat I have had cards become yellow and become brittle in a little as 2 years.

I guess I need to complete an experiment using common cards. I will subject the cards to various elements (acid paper test, sunlight test, cardboard test, and the plastic pen test to see the affects of different conditions on slot club cards.

Scott, Is there any way to get some blank cards from you to show the affects of both front and back?

I have seen some weird stuff occur to cards over the years (I have a couple of cards that were in my wallet that were affected by long-term exposure of the chemicals used in leather tanning.