How instant photographs work

While regular cameras need their film to be processed separately, Polaroid Instant Cameras already contain a film which is equipped with chemicals necessary for photo development. This special type of film has three colour layers which are respectively sensitive to blue, green and red light. Underneath each of them, a developer layer containing dye couplers can be found. All of these layers are stacked on a black base layer and are, at the same time, positioned underneath the image, timing and acid layer. This certain arrangement is of great importance as it is a chemical chain reaction waiting to be set in motion. The component that starts the whole process is called reagent. It is a mix of opacifiers, alkali and white pigments. Before the button on the Polaroid camera is pressed, all of these substances are gathered in the white frame of the later developed photograph. In this way, the film is prevented from exposing prematurely as all of the developing chemicals are kept away until the proper time. After you have taken the picture, the film sheet passes out of the camera through a pair of rollers. These spread the substances of the reagent out into the middle of the film sheet which then react with the other chemical layers in the film. The opacifiers are particularly important for this step as they stops light from filtering onto the layers below so that the film is not fully exposed before it is developed. When the substances are moved downward by the rollers through the many layers of the photo, the exposed particles in each of the layer are changed into metallic silver. Also, the chemicals dissolve the developer dye which begins to diffuse up toward the image layer. These move up from the unexposed layers to the image layer. Simultaneously, other substances of the reagent are working their way down through the film layers. The acid layer in the film reacts with the alkali and opacifiers in the reagent so that the opacifiers become clear. This leads to a visible image in the end. The timing layer slows the reagent down on its way to the acid layer so that the film is given time before being exposed to light. It must be remembered that the first image coming out of the Polaroid camera is initially still grey. It slowly appears because of the refined chemical developing process inside the camera. 

                      

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