This week's How-To Tuesday is about developing film using instant coffee, vitamin C and washing soda.
Photos by Photojojo
"Caffenol" developing, as it's called by those in the know, produces lovely, soft-contrast, black-and-white negatives when used to process either B&W or color film. You get the same results for color slide film, too.
Why is that?
Photographic film is coated with a layer of silver-containing crystals. When you take a photo, light from the scene chemically marks these crystals to be converted into silver metal during the process of film development. Crystals that were hit with more light when the photo was taken convert more readily into the silver metal. Unexposed crystals are later removed, leaving only the opaque metal. This means that the brightest part of the scene that was photographed will be the darkest part on the film, resulting in a negative image.
For color film, this process happens in multiple layers, each of which respond to a different color of light (red, green or blue). Additional chemicals that produce the desired colors are attached to each of these layers. For negatives, the pigments are linked to the areas that were exposed to light (light areas become dark). For slide film, also called positives or transparencies, they are attached to the unexposed areas (dark areas remain dark).
For any kind of film, coffee chemistry will convert the silver but the color-producing compounds are entirely omitted. Therefore, you'll always get a B&W negative.
Found Photography made this very thorough caffenol tutorial video that covers the entire process, even how to properly load the film into the developing tank reel:
But the DIY coolness doesn't stop there. Tom Overton writes that coffee can be used to develop prints, too. Check out his photos and descriptions of the process here.
So, what kind of images do you get from caffenol processing? Here are a couple of examples.
"Caro in Caffenol" by nueh on Flickr.
Photo by Travis Gray on Flickr.
Have you tried processing film or prints in caffenol or other homemade solutions? If so, how did it work out?