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Periodic Graphics

Periodic Graphics: The chemistry of Polaroid photography

Chemical educator and Compound Interest blogger Andy Brunning zooms in on the science behind instant-printing photos.

by Andy Brunning, special to C&EN
May 24, 2024 | A version of this story appeared in Volume 102, Issue 16


Infographic on the chemistry of Polaroid photography. Polaroid film uses three layers of silver bromide crystals, each sensitive to a different color of light. When the correct color of light hits silver bromide, that compound reacts to produce silver atoms.
After the photo has been taken, a pack of chemicals bursts and spreads over the film. The chemicals include potassium hydroxide, which diffuses downward toward the dye layers. There, it deprotonates the hydroquinone developer molecules attached to the dyes.
When silver bromide crystals are not exposed to the color of light they are sensitive to, the deprotonated dye right beneath those crystals flows up to the image layer. But in areas where the crystals are exposed to the right color of light, the silver atoms oxidize the hydroquinone, preventing the dye layer just beneath from diffusing up to the image layer. The dyes combine to create the different colors that make up the image.
After development, the remaining potassium hydroxide reacts with an acid polymer layer to form water and a potassium salt. Other reagents—potassium thiosulfate and uracil—stabilize the photo by clearing unexposed silver bromide, stopping it from reacting further with light.
Credit: Andy Brunning

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References used to create this graphic:

Berg, W. “Polaroid One-Step Color Photography.” Naturwissenschaften (1977). DOI: 10.1007/BF00439885.

Fujita, Shinsaku. “Photography Based on Silver Halides. An Overview.” In Organic Chemistry of Photography, 3–37. Springer-Verlag Berlin Heidelberg, 2004. DOI: 10.1007/978-3-662-09130-2_1.

Jarvis, Lisa M. “What’s That Stuff? Instant Film.” Chemical & Engineering News, March 23, 2009.

A collaboration between C&EN and Andy Brunning, author of the popular graphics blog Compound Interest

To see more of Brunning’s work, go to To see all of C&EN’s Periodic Graphics, visit



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