Wet Plate Collodion
Exposing and developing hand-coated collodion plates while still wet, yielding detailed negatives, ambrotypes, or tintypes.
Wet plate collodion is a photographic process in which a glass or metal plate is coated with collodion, sensitized in silver nitrate, and exposed and developed before the coating dries. Frederick Scott Archer, an English sculptor dissatisfied with paper negatives, published a working method in The Chemist in 1851 and left it unpatented, although Gustave Le Gray had proposed collodion a year earlier. Joining the daguerreotype's fine detail to the negative's reproducibility, with exposures of seconds, it dominated photography from the mid-1850s until gelatin dry plates displaced it in the 1880s. It produced glass negatives, usually printed on albumen paper, ambrotypes, thin glass negatives backed with black to read as positives, and tintypes on black-lacquered iron.
Coating, sensitizing, exposure and development must all happen within about ten to fifteen minutes, so outdoor work required a portable darkroom. Prints were made by contact, so large prints demanded equally large plates. The coating responds mainly to blue and ultraviolet light, rendering skies blank and reds dark. Hand pouring leaves uneven edges, drip lines, swirls and an uncoated corner where the plate was held. Ambrotypes and tintypes are unique, laterally reversed images with creamy highlights. Roger Fenton printed The Crimean War Photographs from wet collodion negatives, while Julia Margaret Cameron kept streaks, smudges and fingerprints that contemporaries treated as faults.
Cameron's marks were criticized in her lifetime as careless and are now read as deliberate traces of the maker's hand, a tension that persists in the process's revival since the late twentieth century. Sally Mann began making glass negatives in the late 1990s and kept chemical streaks and blemishes as expressive elements, and the revival is often discussed in terms of nostalgia. Dry-Plate Collodion plates were treated to stay sensitive after drying and could be exposed later, at the cost of much longer exposures. Albumen Silver Print names the paper print often made from a collodion negative, so a vintage print may carry both tags.