Reviewing some old photos of family, I noticed that when viewed from an extreme angle, the black of the prints looks iridescent black. Is this just an effect of the silver--it almost looks as though it is solid metal. I only ask because I never notice this on any of my prints FB or RC. The photos were made in the early 1910-1930's. I'm wondering if this is the result of a certain printing process.

Taking a study break,