Deterioration and Preservation of Negatives, Autochromes, and Lantern Slides
General Information Genthe photographed his subjects in both black-and-white and color, using a variety of formats. Photographic negatives are made of an image-forming substance or emulsion, which is coated onto a base or support. The bases found in the Genthe collection are either glass, nitrate film (nitrocellulose), or safety film (cellulose acetate). Each type of negative base has a different aging process with a...
Autochrome photography flourished from 1907 to the 1930's. Each autochrome is a unique transparency image; there is no negative. Autochrome plates were created by coating a sheet of glass with microscopic starch grains dyed red, green, and blue. These formed a screen of color particles. Carbon black was applied over the plate, filling in the spaces around the starch grains. Then a silver gelatin...
This image of Margaret Severn is from a fractured glass lantern slide. Lantern slides are positive glass transparencies made for projection. Genthe used these "magic lantern slides" for lectures.