Leon, "patina" seems right and was a good word choice. It appears a definite authentic has a brown undertone, under the white.
As far as cards being printed on various paper stocks back then, I have a set of W517's (minus four), some with several variations. The thickness, color, etc of the paper varies variation to variation.
Another thing about the card in question, the Ruth's Grip #5, is that it has a strong vintage odor.
A Ruth collector in Maryland has a set of authentic factory cut singles in Beckett holders, and his neighbor has some too. Overall, he's handled approx twenty. When I spoke to him about it, he said the paper is more like a '33 Goudey and less like a '34 Goudey. He explained why he said that, but just out of curiosity, do y'all know why?
I have an E121 type card and '33 Goudeys, so I'll get some comparison work done with them today.
A Goudey Ruth in PSA 3 is an awesome card, but even so this card is easily the most stunning I've ever owned.
