Caffenol

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Caffenol is the name of a developer liquid for black and white films based on caffeic acid . Caffenol is a so-called alternative developer, as its components are available in every drugstore or supermarket . In addition to caffeic acid from instant coffee , Caffenol contains washing soda ( sodium carbonate ), which acts as a pH regulator for the solution. Caffenol emerged as a result of research at the Rochester Institute of Technology (RIT) in the mid-1990s . The first report that you can develop films with coffee comes from 1937 and was an April Fool's joke ( Die Fotoschau , April 1937, page 14).

variants

Caffenol C: To accelerate the development process and to increase the image contrast, Caffenol can be mixed with vitamin C ( ascorbic acid ), which is itself a developer substance and is also used in commercial developers. The development times then correspond to those of conventional chemicals. The superadditivity is used when two developers are used. When two developers are used at the same time, development becomes smoother and faster.

use

The developer solution is used undiluted immediately after preparation. The exact development times must be checked for the film material used. Caffenol develops comparatively slowly (at least 30 minutes for black and white films) and delivers very soft, balanced negatives. With Caffenol C the development time is reduced to 10–12 minutes with steeper gradations and sometimes very coarse grains.

Current status

Today (2013), Caffenol-C is widely used, as the combination with vitamin C offers clear advantages. There are now metric recipes in grams / liter, which allow a far more reliable production than with the traditional teaspoon method. In addition to instant coffee, vitamin C powder and washing soda, iodized salt or potassium bromide (from regular photochemistry) are also used as anti-fogging agents in order to achieve very good results even with highly sensitive films.

Web links

Individual evidence

  1. ↑ Williams, S .: A Use for that Last Cup of Coffee: Film and Paper Development , 1995, accessed December 19, 2011