Transparent celluloid roll film
1889 (Eastman's celluloid film; Goodwin's competing patent applied for 1887)
Gelatin emulsion on a thin, flexible strip of celluloid replaced glass. It made small cameras possible and, cut into strips, became cinema film.
How it began
Eastman’s first roll film used paper as a temporary support: the emulsion had to be stripped off the paper after development, a fiddly job done at the factory. In 1889 his chemist Henry Reichenbach patented a clear, flexible base of nitrocellulose. A clergyman, Hannibal Goodwin, had applied for a similar patent in 1887, and his heirs later won a large infringement case.
How it works
The film base is a thin transparent sheet. A gelatin silver halide emulsion, like that of the dry plate, is coated on one side. Because it bends, many exposures fit on one roll that winds through the camera, and after development the negatives can be printed directly.
Why it mattered
Flexible film made the hand camera, and photography for everyone, practical. Cut into narrow strips and perforated, it also made motion pictures possible, and 35mm cine film later became the format of the Leica.
Limits and what replaced it
Nitrocellulose is highly flammable and decomposes with age; many early films and negatives have been lost to fire and decay. Cellulose acetate “safety film” took over by the early 1950s, and polyester bases followed.
Today
Film is still made on flexible bases, now cellulose acetate or polyester instead of flammable nitrate.