When working with wet photographic plates, Swan noticed that heat increased the sensitivity of the silver bromide emulsion.
By 1871, he had devised a method of using dry plates, and substituting nitrocellulose plastic for glass plates, thus initiating the age of convenience in photography.
Eight years later, he patented bromide paper, developments of which are still used for black-and-white photographic prints.

In 1864, Swan patented the transfer process for making carbon prints, a permanent photographic process.
By adding the transfer step, Swan was able to easily make photographs with a full tonal range.
When working with wet photographic plates, Swan noticed that heat increased the sensitivity of the silver bromide emulsion. By 1871, he had devised a method of using dry plates, and substituting nitrocellulose plastic for glass plates, thus initiating the age of convenience in photography. Eight years later, he patented bromide paper, developments of which are still used for black-and-white photographic prints.
In 1864, Swan patented the transfer process for making carbon prints, a permanent photographic process. By adding the transfer step, Swan was able to easily make photographs with a full tonal range.
Joseph Swan