How Is Silver Bromide Used in Photography?
Silver bromide is used in photography as a component of an emulsion that helps develop a photographic image. Silver bromide is sensitive to light, and when suspended in gelatin, silver bromide’s grains create a photographic emulsion. When exposed to light, silver bromide decomposes and as a result, it preserves a photographic image.
In 1874, J. Johnston and W.B. Bolton invented negative emulsion using silver bromide for chemical development of photographs. Within 4 years, Charles Bennett improved the method and the speed of developing the photographic image increased. The discovery was that when aged at 89.6 degrees Fahrenheit, the emulsion made with gelatin and silver bromide becomes more sensitive to light.
To use silver bromide in photography, it needs to be made into a photographic emulsion. This is formed on cellulose acetate, with the help of a thin layer of gelatin. Gelatin is needed to increase the emulsion’s light sensitivity.
After silver bromide creates a photographic image, the image needs to be developed. Grains of silver bromide, which have reacted to light, become metallic silver, whereas those unaffected by light do not change. These remaining grains are washed away in a fixing solution.
The gelatin and silver bromide method of photograph development was an important step for astronomical photography, because it allowed objects that emit faint light to be captured on photographic film. Scientists used the silver bromide method to produce the first good images of Jupiter and Saturn during 1879 and 1886.
