This is the second installment of a series in which David Vestal gives insight into historic photographs selected from Great Photographs from Daguerre to the Great Depression, published by Dover Publications and used with their permission.

Skip to the 1860s. Photography had changed. The daguerreotype had largely given way to the ambrotype, in which the silver of a very thin negative on glass was seen as light tones against black velvet. Like the daguerreotype, it was a one-of-a-kind photo delivered in a little frame. Dover didn’t identify the methods used for its photographs, but I saw no ambrotypes among the ones I printed.

The tintype used the same principle as the ambrotype: a thin silver image on black-enameled iron. Tintypes were small, cheap and quickly made. Many tintypes of Civil War soldiers survive and are prized by collectors. Tintypes were made until about 1950, when itinerant street photographers switched to Polaroid.

The main photographic medium from the 1860s through the 1880s was the wet collodion process. A glass plate coated on one side with collodion was sensitized in a silver bromide bath, then placed in a light-tight holder with a removable dark slide and a draining groove, then placed in the back of an aimed and focused camera and exposed at an aperture and time guessed at by the photographer. The exposed plate had to be developed, fixed and washed before the collodion could dry and become waterproof. Every exposure was also an exposure test, so photographers tended to become good guessers. They also coated their own printing paper with its sensitive emulsion, and their contact prints were the same size as their negatives. Photographers could be recognized by their stained hands and clothes.The plates were still sensitive only to blue light and ultraviolet. No one knew about the electromagnetic spectrum. When the photographers guessed right, wet- collodion photos could have superb photographic quality.