by Myya McGregory
Do you remember Polaroid cameras? Once adored by all, they are now widely considered obsolete in a world of digital photographs and instant uploads to Facebook. At the time the concept the concept perfectly captured the idea of instant gratification. People could finally take a photo and watch it develop on the spot.
Instant cameras like the Polaroid essentially contained a miniature developing studio in a box. Keep in mind that in the pre-2000 age “miniature” had not yet reached its full potential.
Developing instant film involved a series of chemical reactions strategically triggered at different times during the development process. The film contained three layers of silver bromide crystals. Each layer would be sensitive to a primary color because a hydroquinone dye the color of its negative would be beneath each layer. This way, the positive color is absorbed.
Bromine leaves behind a silver cation which is reduced by light once the film is exposed. If a given color is exposed, its negative (or complement) cannot filter through. Once the dyes have diffused to the surface of the film, the film is ejected and covered with potassium hydroxide (which gives Polaroids a greasy feel before they are developed). This base reacts with the weakly acidic hydroquinone dyes as it diffuses through the film. The dye molecules then diffuse up to the surface through capillary motion. Potassium hydroxide is then neutralized and unused silver bromide is dissolved by potassium thiosulfate and uracil.
The thickness of each silver bromide layer and the mixture of developers is crucial to determine when the reaction is quenched and how clear the resulting image will be. As the “Impossible Project Team” rushes to recreate the beloved instant sensation, they are coming to find out that Edwin Land and the developers of Polaroid truly had perfected instant film. If only they had foreseen the digital age …