I decided to get my question about the capacity of Caffenol as a print developer by running a test. I selected a negative shot on Tri-X from 1991, developed in Caffenol Delta-Std. It was shot with a Bolsey B2 rangefinder. I am making prints on Ilford MGRC cut into 4x5 sheets.
The first image I did as a reference, traditionally developed in Dektol 1:2. I used 40Y 80M for contrast.
Next I mixed up a 16 ounce batch of Caffenol Delta-Std, or at least close to it: 22 g instant coffee, 10 g Vit C, 12 g washing soda. The Vit C are tabs with filler.
Next I did an exposure test and developed it in Caffenol for 12 minutes. I use a Unicolor tube, 8x10 size, on a Unicolor agitator base. I rinse with water, 5 rinses, and then fix for 3 minutes, again in the tube. I selected an exposure time, 12 seconds at f/8. (I am using a Beseler 23C with a 50mm Schneider with filters in the drawer below the lamp.)
I figure that at this point I have put 1 print through the Caffenol developer, 20 square inches. Now I print 10 prints, all the same exposure, and process them at 2 at time. I figure that this will exhaust the developer a bit faster than doing this one at time. I stir the developer and then pour about 4-5 ounces into the tube for each batch.
Batches 1,2, and 3 look pretty similar but by batch 4 it starts to look a bit thin and even more so with batch 5. I am concluding that 16 ounces of of developer, reusing it each time, is good for about 140 square inches.
Here are the photos from each batch, named by batch number, shown 1-5, left to right.
I think the next thing to look at is using it as a one-shot developer. The little trough in the tube holds 4 ounces and I am curious at to whether 4 ounces would be adequate for an equivalent to an 8x10 print, or 80 square inches.
I do like using Caffenol for my old, expired film, just because, especially if I'm shooting with my Bolsey B2, again just because. Using it as a print developer is an interesting tool to have in my kit but I'm not sire that I'll be using all that much.