The printing of the photographer’s or manufacturer’s name on the back of real photos was an expensive proposition.This practice was only cost effective on cards printed in large numbers; individuals and small photo studios could rarely afford to do so. While many amateur photographers numbered their cards this was most often done by larger studios.Observing this shiny crust, no mater what the color, is a quick and sure way of telling if you are looking at a real photo.
Most old photo papers used silver in their emulsions.
As time passes this silver tends to migrate to the surface of the print creating tell-tale metallic patches.
Deltiology, the hobby of collecting vintage postcards, is one of the fastest-growing collectibles hobbies.
Old postcard collections interest collectors of antiques, memorabilia and ephemera; collectables such as old vintage postcards are used by museums and historians to document what was.
This could go on for generations, and it is not uncommon to find the same photograph attributed to three different artists.
While today this would lead to lawsuits, copyright was uncommon and rarely enforced at the turn of the 20th century.
If the name appears on the photo itself, it is because the negative was scratched into or written upon but it could have been printed at any time.
Some companies were still printing real photo postcards in the 1970’s from negatives taken in the 1890’s.
In printed images the grey areas are usually made up of black marks that are spaced to create the optical illusion of greys.