'66 semi-high back variation? Different print run? Reprint?

[rsdill2]

Flipping through my '66 set I noticed something. Several of the semi-highs (447-522) in my album have different backs to them. Most of the backs are a more faded off-white/cream color. However, there are some (I'd say about 20%) with a distinctly different back color. These are much more bright white. There is also a very slightly different color scheme on the fronts as well - you can really tell a difference in the players faces

Another slight difference is in the paper stock. The bright white backs are a little bit "flimsier" and seem to be printed on a thinner card stock.

I don't see any listing anywhere of a back variation for this series. Was this a different print run? They all seem legit to me and I couldn't imagine '66 semi-high reprints to be that prevalent in the hobby where I'd have this many of them (and I got them all from reputable sources).

Curious if anyone has any insight on this. Do you notice these differences in your '66 set? Any knowledge about prior research on this variation?

I've uploaded some scans to my photobucket.

Front scans

Back scans

[brett 75]

Interesting ,I found the same thing on some of the 1966 cards I received as a b-day present last year . I figured maybe the had come from packs and hadn't been handled after first coming out of the packs. ? The backs on the others look almost dirty compared to the bright white backs. I'm sure someone here can explain it . Anyone else notice these?

[toppcat]

Just different card stock. Those brilliant white cards tend to stay brilliant; it's good quality cardboard. There are numerous Topps sets with this stock but it was sporadic and often only for a single print run or series. I suspect they used it if they could get it for the price they wanted, otherwise an inferior grade was used.

[doug.goodman]

I'm not sure if anybody collects that "variation", I know that even I'm not that crazy.

But I don't know about Al...

Doug

[ALR-bishop]

If they are not on Doug's list I don't want them

[rsdill2]

Interesting...thanks for all the replies.