I need help figuring out what I did wrong. Here's what happened:
I have three 120 rolls that need developing: two rolls of Delta 400 and one of HP5. I used the Delta-STD recipe and developing times to develop a roll of Delta and it seems fine. Here's the chart I used for the data:
http://www.caffenol.org/film-development-chart/According to this chart, HP5 should use the STD recipe as well, but with double Vitamin C and one more minute of developing time.
I have had no problem reusing Caffenol a few times (a different recipe, though), so I kept the batch from the roll of Delta, added the extra Vitamin C, and developed the HP5. Did everything as usual, finished fixing and rinsing, and pulled the reel out.
Nothing. Completely blank - clear (the fixer's fine) but not even a hint of an image. No markings either, so not a camera issue (especially since the Delta came out fine. All rolls were shot with the Mamiya C330 I just got for Christmas.)
Should I not have reused the same batch? Could the extra Vitamin C have done something? Was 10 minutes too short?
I was planning on using the Caffenol C-M recipe for the other roll of Delta 400 so I could compare them (same film, same camera, different recipe) so I was going to throw the other batch out anyway.
I'm annoyed that the whole roll was wasted, but at least it was just a test roll - the first roll I put through the Mamiya and shot at home, so I can easily replicate the shots. I suppose I would have made this error at some point and so it's better now on a test roll than later on some more important shots.