Capturing a fleeting moment onto a tangible surface for later recollection stands as one of humanity’s most transformative inventions. This material record of people, lives, and memories was not the result of a sudden discovery, but rather the culmination of years of scientific inquiry and experimentation. Long before photography became a formal discipline, many pioneers were seeking ways to create permanent impressions of the images they observed through pinhole cameras or camera obscura devices.
Around 1834–1835, William Henry Fox Talbot was among those driven by a desire to preserve the beauty of nature he so deeply admired. His efforts were informed in part by earlier scientific knowledge—particularly the accidental discovery by Johann Heinrich Schulze in the early 18th century, who demonstrated the light-sensitive properties of silver nitrate.
At the same time, inventors like Joseph Nicéphore Niépce and Hippolyte Bayard were independently exploring methods to capture real-life images onto physical surfaces.
The first official announcement of photography came with the creation of images on metal plates—a process known as the daguerreotype, named after its inventor, Louis Daguerre. These photographs were unique in their dual nature: depending on the angle of light, the image could appear either as a positive or a negative. This optical phenomenon made daguerreotypes simultaneously captivating and technically complex.
All the photographic processes that were developed after daguerreotypes involved a negative which was used to create a positive. These negatives were initially on paper or glass and then later on different kinds of films.
Glass plate negatives
Glass plate negatives represent a pivotal chapter in the history of photography. Introduced in the mid-19th century, they were the primary medium for capturing photographic images before the advent of flexible film. These fragile yet incredibly detailed negatives have become valuable cultural and archival records. For conservators, understanding their structure and chemistry is crucial for ensuring long-term preservation.
Glass plate negatives were commonly used between the 1850s and 1920s. Two main types existed:
- Wet Collodion Plates (1851–1880s): Exposed and developed while still wet.
- Dry Gelatin Plates (1870s–1920s): Could be stored before and after exposure, marking a significant leap in photographic convenience.
Despite their differences in handling, both types share a similar multilayered construction that poses unique conservation challenges.
Film negatives
Film negatives have played a monumental role in capturing the visual memory of the 20th century. From family portraits to cinematic masterpieces, film negatives—thin, light-sensitive strips that capture inverted images—revolutionized both photography and motion pictures. Understanding the evolution of film negative materials is vital not only for photographers and historians but also for conservators working to preserve these fragile yet invaluable records of human experience.
Cellulose Nitrate Film (1889–1950s)
- Invented by George Eastman (Kodak) in 1889.
- Made of cellulose nitrate, a flexible, transparent plastic base.
- Revolutionized portability and mass production in photography and cinema.
Cellulose acetate
Diacetate and Triacetate Film
- Developed as “safety film” to replace flammable nitrate.
- Made from cellulose diacetate, later cellulose triacetate, plasticized with additives for flexibility.
- Kodak began large-scale production in the 1920s.
Polyethylene Terephthalate (PET) Film
- Introduced in the 1950s and now the dominant support for photographic and motion picture negatives.
- Marketed under names like Mylar, Cronar, and Estar.
Film negatives: Flat to Rolls
