An example of a T206 card chemically altered on ebay

[steve B]

It's been subjected to some chemical. Possibly actual bleach.

The part that makes it fairly certain is that most blue inks have dyes or pigments that don't fade all that much. It is complicated by the 1910 era being right around the time a lot of new synthetic dyes were being invented.
Many modern dyes do fade, but are used because they're far cheaper than the old natural pigments/dyes.

If it was from light, I'd expect to see the red on the back edge of the hat faded as well. Red inks usually are among the worst for fading from light exposure.

The red ink there is within the affected area, but isn't faded. It is blurred, so whatever did it was able to partly dissolve either the ink or the coating on the front of the cardstock.

On the back it's a great example showing how colors are mixed. In the faded area the blue is gone, but the black remains. Dark blues are usually made by mixing a more normal blue with black ink. And since most black ink of the era is made with carbon, it simply won't fade at all. Whatever did the bleaching removed the blue and left the black.

Hard to say whether it should be graded "A" or 1. The damage could be accidental, and could be from back then. Card left in shirt pocket, mom (or whoever) finds it as it's going into the washtub and pulls the card out before it gets totally soaked. Or it could be from a failed attempt at whitening the borders.

With the creasing I'm inclined towards the first explanation. Assigning intent to a technical subject is often difficult. In this case, I think the 1 is appropriate, as the damage is a stain of sorts.
If it was a big ink stain from a pen in the pocket leaking the 1 wouldn't really be questioned.

Steve B