Brewing up Photography: Using Coffee to Develop Film

By Keith Michael Krise and Scott A. Williams

When you wake up in the morning, you might hear and smell coffee brewing in your kitchen. Would it surprise you to learn that the same cup of coffee, along with some other common household chemicals, can be used to develop camera-friendly films?   

Thirty years ago, chemistry Professor Scott Williams and his students found that drinks like coffee contain molecules that can be used to develop film.

Developing photographic film changes a temporary image into a permanent one. To do this, the freshly exposed image must be ‘developed’ so it is no longer light-sensitive. In black-and-white photography, this is done by reacting to the film with a compound (sodium thiosulfate) to inactivate or disable any remaining photoactive silver ions or particles that produced the first or “negative” image. 

There are many examples of organic molecules (which are made of carbon, hydrogen, and sometimes other elements) that have been used as developers, such as hydroquinone and catechol (Figure 1).

Coffee contains many compounds, but one of particular interest is caffeic acid (Figure 2). Does caffeic acid look like any of the organic compounds that have been used as photographic developers? Yes! It looks like a catechol molecule. 

For coffee to be used in the caffenol method, the film developer solution must have a high pH (around 11). Household chemicals including baking soda (sodium bicarbonate), drain cleaner (potassium hydroxide), and washing soda (sodium carbonate) can be used to achieve this. Note: sodium carbonate and potassium hydroxide should be handled with care, and only by an adult.

The sources of many developer compounds are processed oils, which contain molecules that can be bad for the environment. Using chemicals from coffee is safer for the environment, as coffee comes from the beans of the Coffea plant!

References

1. Williams, Scott. “A use for that last cup of coffee: film and paper development.” DCCT, September/October 1995. Available at https://repository.rit.edu/article/1124/.
2. Witten, Nichole Marie. The Chemistry of Photography (2016)

Keith Michael Krise, Ph.D. is an Associate Professor of Chemistry and Biochemistry, Gannon University. Scott A. Williams, Ph.D. is a Professor of Inorganic Chemistry and Director of the Materials Science and Engineering Graduate Program, at Rochester Institute of Technology.