A couple of things to add...
First, I also bought most of my C52s from a gentleman in Canada. I’m not sure if that adds any credence to the C52s are a Canadian issue theory but I figured I’d add that.
Also, I’ve never seen any discussion of back color variations but has anyone else noticed? About a third of my backs are white but most are brown. I don’t *think* this is due to aging as it looks like genuine paper stock differences to me. I could be wrong. Thoughts?
Here’s two Sellen cards with different color backs:
And more...
