Wet-plate process (or wet-collodion negative). In 1851, F. Scott Archer described a collodion binder to hold silver iodide on a glass support plate (potassium bromide was later added to improve photosensitivity). Archer's ‘wet-plate’ process was cumbersome, but produced inexpensive, high-quality negatives, and was the standard plate technology from 1855 until about 1881, when it was superseded by gelatin silver bromide dry plates. In the 1850s and 1860s, various formulae were proposed for ‘dry’-collodion negatives incorporating tannin or acidic sugar preservatives such as raspberry syrup, but the poor keeping properties and slow speed of these plates limited their use.
— Hope Kingsley
