Instant film is pretty much what it sounds like. When an instant film camera takes a picture, the film it uses develops right away, before the photographer's eyes. This one-stop photo process was invented by Edwin Land. a scientist who co-founded Polaroid, the company that would one day market his instant-film creation, the Polaroid Land camera.
When you take a photo with instant film, reagent chemicals are spread on the film as it leaves your camera. The chemicals move downward through additional layers of silver compound, changing the particles into metallic silver and obtaining color. At the same time, above the reagent material are a number of layers as well: the image layer, the timing layer, the acid layer and the clear plastic cover. The image layer accepts the dyes from the colors below using the white pigment in the reagent to shine through. The timing layer slows the process so that the picture doesn't get developed before all the colors are in place. The acid layer removes the opacifiers from the film that originally blocked the light. As the opacifiers clear up, you can see the image slowly emerge on the clear plastic.
Interestingly, Land came upon the idea for an instant camera in a burst of inspiration, all thanks to his daughter. In the early 1940s, Land's three-year-old daughter wondered aloud why a picture the scientist had just taken wasn't already available to see. As often happens with great inventors, a simple thought spurred a complex mind. Land went out for a walk following his daughter's question. Amazingly, it took him only one hour to see in his mind's eye the necessary components for an instant film printing system. And, as luck would have it, even Land's patent attorney happened to be vacationing nearby [source: National Academies Press].
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