Yellowing Borders 1972-1974

[danx]

I am primarily a 1970's collector and have noticed over the past 6-7 years an issue on cards with white borders.

There is an obvious yellowing on the borders of cards in the marketplace, more and more. Noticed it mainly for 1972-1974's - graded and ungraded.

Cards in my PC are stored in sleeves or are graded and I haven't noticed deterioration on those.

Has anyone else noticed this? I know these are 50 year old cards, but some examples on sale are crisp and white and some have this acid degradation.

I try to avoid bad examples - does this bother anyone else? Do you guys think this effects value? Have any collectors of the 1960's seen this over time? Seems like some 1964's I have are about 50/50, but other years don't suffer as much. Is it paper stock from year to year? Cigarette households? Bad storage?

Again - as a 1970's collector, I didn't see this as much on the 1972-1974's even 5 years ago and am noticing it more and more, now...