How does instant photography work?

 

Polaroid film is essentially one big chemical reaction. When you take a picture with a Polaroid camera, the shutter opens and quickly captures the image. It takes in the patterns of light and imprints the image onto plastic film that is covered with silver compound. This is when the photo develops. On the film there are three silver compounds. The top layer is sensitive to blue light, the next layer is sensitive to green light and the bottom layer is sensitive to red light. When you expose the film, the sensitive grains at each layer react to the light of that color, creating a chemical record of the light and color pattern. Each color layer is situated above a developer layer which contains dye couplers. There are four chemicals waiting to react, namely the developer layer, the acid layer, the timing layer and the image layer. The chemicals get set off by a reagent. A reagent is a substance used in chemical reaction to detect, measure, examine or produce other substances. It is a mixture of white pigments, opacifiers and alkali. Opacifiers and alkali are especially important since the opacifier, a chemical that protects a newly ejected image from light and then slowly dissolves away, works as a light blocker and the alkali as an acid neutralizer. The reagent is collected in a blob at the border of the plastic film sheet, away from then light-sensitive material. When you snap a photo, your instant camera automatically ejects the picture in between two metal rollers. As the film exits, these rollers push the reagent on the white plastic borders onto the silver compound, spreading the reagent across the film. This starts a large chain of chemical reactions. First, the reagent causes the four layers (developer, acid, timing and image layer) to react. This then causes the silver compound layer to process, thus producing blue, green and red light patterns which turn into an image. The timing layer protects the film from light exposure until the film is fully developed. This final reaction is what causes the illusion of the image being formed right before your eyes. 

  

355 words