An early photographic technique invented by Englishman Frederick Scott Archer in 1851. He was trying to capture his own portrait sculpture with more detail than calotypes. They are known as Ambrotype, on glass and Tintype, or ferrotype on black lacquered metal.
Wet Plate Collodion - Victory Adjusting Her Sandel (415 B.C.)
Wet Plate Collodion - Portraits - Shawl 1 and Shawl 2 as exhibited at the Warrington Contemporary Open