Question: I just inherited a patch of old family photos that are on blue paper. Can you tell me what type of photograph this is and when they were taken?
Answer: The photograph you are referring to is a Cyanotype. This photograph was a popular style ca. 1890-1910 from the albums I have seen. This cyan-blue color paper print added that dimension of color that the albumen style print did not. To learn more about cyanotype photographs: http://en.wikipedia.org/wiki/Cyanotype