[benjulmag]

I was thinking of something a bit different.

If a century old card is trimmed, wouldn't its trimmed border(s), newly exposed to the atmosphere, exhibit different chemical characteristics than the untrimmed borders, which difference could be detected and measured?

I do not have any expertise in chemistry, so the above is a question, not a statement. If trimmed borders do in fact exhibit chemical differences, I would think that would be a great way to detect alterations. And one would not even need a base mark. Assuming at least one of the borders is untrimmed, all one would need to look for is whether there are any different chemical characteristics between the borders of the same card.

I would think too one could use the same concept to detect cards that had been recolored.

I get it that do this one would need to take the card out of the slab. But so what, if that is the price it takes to know with a much greater degree of certainty if the card is altered?