Developing with Coffee

For a while I'd been using something called Rodinal. It's one of the oldest film developers you can still buy, thought I use it because its cheap. Turns out its cheap and old because its about as chemically complicated as a blank piece of paper, and for a while I'd been reading people homebrewing rodinol with Paracetamol, coffee and even tomato relish... It was too stupid for me to have not tried!

After some research I found that a coffee based developer named caffenol which would be simplest and most effective one to try. The recipe was based off 3 components: instant coffee, vitamin C powder and washing soda. There's plenty of guides all over the internet, so I had a go and blank. The whole role was dark black- which is the last thing I was expecting to happen. I would have expected the coffee solution to have not developed the film which would leave the roll transparent or blank, but it being dark black indicates it was actually severely overdeveloped.... 

The only thing I was suspicious of was the washing soda I'd used. I'd read something about using caustic soda, so that's what I'd chosen to use. Reading further it seemed there was some confusion around caustic soda or soda ash, or sodium hydroxide and sodium carbonate to be specific. Reading really really deep now it turns out the Coffee and vitamin C are the active agent, and the washing soda is the pH balancer. Essentially all developers have an ideal pH that they work best at, higher the pH the faster they work and lower the slower. Rodinal is known to be fairly aggressive pH developer at around 11.8pH. Knowing this odd fact, I double checked and sure enough caustic soda has a pH of around 14, while soda ash is around 11-12pH.... Indeed it seemed the caustic soda was my problem. Knowing this I had another go, and what do you know... it actually worked!