I'm trying to date this picture and was wondering if the process that was used to produce it can somehow date it.
I've also noticed this type or process was used on some postcards, Birthday cards etc.. When tilted in the light some areas of the picture changes to a bright blue.
The item below is a picture I bought at a flea market thinking it looked a lot like a older Alexander Graham Bell. (Bell Died in 1922)
With the photo being of this type could it aid in dating it?