How Instant Photographs Work

 

In 1947, Edwin Land introduced a great innovation to the world – instant cameras. This camera with a film that developed itself in a matter of minutes was a huge success. This text will determine the process inside instant films, which may seem like magic but is actually a chemical chain reaction.

Instant camera film has three layers that are sensitive to different colors of light. Underneath each color layer, there is a developer layer containing dye couplers. All of these layers sit on top of a black base layer, and underneath the image layer, the timing layer and the acid layer. This arrangement is the chemical chain reaction waiting to be set in motion. The reagent, which is a mix of opacifiers (light-blockers), alkali (acid neutralizers) and white pigment, starts the reaction. It is placed above the light-sensitive layers and below the image layer. The reagent material is collected in a blob at the border of the plastic film sheet. After a picture is taken, the film sheet passes out of the camera, through a pair of rollers. These rollers spread the reagent material out into the middle of the film sheet. When it is spread between the image layer and the light-sensitive layers, a reaction with other chemical layers in the film takes place. The opacifier material stops light from filtering the layers below, so the film is not exposed before it is developed. The reagent material moves downward through all layers which causes the change of the exposed particles in each layer into metallic silver. Then, the chemical dissolve the developer dye and it begins to diffuse up toward the image layer. The metallic silver areas at each layer grab the dyes so only the dyes from the unexposed layers can move up to the image layer. At the same time other reagent chemicals are working through the film layers above. What makes the image visible is the acid layer in the film reacting with the alkali and opacifiers in the reagent. The timing layer slows the reagent down on its path to the acid layer and gives the film time to develop before it is exposed to light. Through this final chemical reaction one can see the image slowly coming together although it is already fully developed underneath. However, the opacifiers clearing up creates the illusion that it is forming right before one’s eyes.