Calotype

William Henry Fox Talbot patented a photographic process in 1841 that led to a stable negative image. The process involves exposing a sheet of sensitized paper in the camera then developing, fixing, and washing it. The stable negative image could be contact printed.

Though calotypes are soft and hazy, with visible paper fibers, the invention revolutionized image-making by making it possible to produce multiple prints from one negative image. It was also used as a means of making copies of drawings and documents. The process remained in use through the 1850s, when it was replaced by the albumen silver print.