I have a very nice signed 5"x 7" sepia tone (or maybe it's just old as dirt) photo of Al Jolson. I have read that authentic Jolson signatures are not as common as one might think--especially considering what a colossal star he was. Are Jolson signatures that rare? Also, I've read it is nearly impossible to find a signed photo of him in blackface. Any particular reason why?
Thank you in advance for any comments/input.