Whats the difference between wet-plate (collodion) and dry-plate tintypes (like Rocklands)?
From Robert Leggat’s “A History of Photography” (1999): “The development of the Collodion process marked a watershed in the development of photography. However, this wet-plate process had limitations, one being that it was necessary to keep the collodion moist. For a number of years several attempts were made to discover ways of keeping the collodion moist for long periods. The materials tried included unusual ones like licorice, beer and raspberry syrup! Some success was achieved by using a mixture of bromide in collodion. The ideal binder would be one which enabled the plates to be used only when dry. It was not until 1871 that the next breakthrough was achieved by Dr Richard Leach Maddox, when he began using gelatin. In fact, as far back as 1850 Robert Bingham had suggested the use of gelatin, but this idea had not been taken up at the time, presumably because of the announcement of the collodion process the following year. “Gelatin is a protein obtained from animals, which is trans
