How instant photographs works?
The instant photographs is a type of photography that generates a developed film image. The most popular types made by Polaroid Corporation. The invention of modern instant cameras is generally credited to American scientist Edwin Land in 1948. To capture a photo in color with a polaroïd we need a polacolor film. The polacolor film is composed of a negative and a positive. The negative is composed of three doubled emulsion layers which are composed of silver halides and dye couplers, which adsorb to the surface of the silver halides, make the crystals sensitive to different colors. In addition to multiple emulsion layers, real films have other layers that are not sensitive to light (top-coated with UV blocking or anti-scratch coatings layers). Each emulsions is sensitive to three colors: the one is blue sensitive, another is green sensitive, and the last is red-sensitive. Below the blue layer is a yellow filter. For example, the blue light affect the emulsion layer which is blue-sensitive and transform the silver halides on this layer to metallic silver (developed silver). All of this without affect the other emulsion layers. The process is the same for others layers. Then, when we pull on tap, a reagent of alkali spills on the negative and the positive. The alkali penetrates the layers of the negative and spills the dye couplers, which will reach the printing paper. The silver halides become metallic silver and the dye couplers is blocked on the layer. Both dye couplers and silver halides exposed intermingle to form colored dyes. The process lasts 30 seconds. At the end, the alkali gets in touch with an acid photographic fixing agent on the printing paper. This acid fixing agent stops others chemical reactions and fixes the formed color dyes. Finally, we obtain a luminous colored picture.
[300 words].
Anaïs Auger.