After several days of frustration and a few rolls of sacrificial film, I'm pleased to have finally gotten to the point where I can say that using mint and/or similar plant based materials is a totally viable way to develop film if you want to go in that direction. Obviously, it took many years of experimenting by a community of enthusiasts to get coffee-based developing from a classroom experiment in the mid 1990s to where it is today. The use of other phenol-containing plants like mint may follow a similar path, who knows? You'll have to decide for yourself if it is worth it. As for me, I feel like I now have a working formula that I can use to get reproducible results from properly exposed film, and that is good enough for the time being. Of course, there are plenty of things still to be optimized, as well as plenty of possible plants to consider other than mint (a topic which might be interesting to explore for a site-specific project).My process for putting the developer together is pretty simple, and goes like this...
First, gather up about 100 g of mint leaves from your garden, chop them fine, and pour over about 200-250 mL of boiling water. Let this mixture steep for an hour or so. You'll have a very strong mint tea at this point. Meanwhile, add about 40 g of washing soda (sodium carbonate) to another 200 mL of water. It will take a minute or so for the solution to clear and it will feel warm to the touch. Next add 10 g of vitamin C to the carbonate solution. Gas will evolve when you do this, so don't be concerned and just let the process dissipate naturally. Then add the carbonate/vitamin C solution to the mint tea and bring up the volume to about 600 mL with water. That is a good starting point. I developed the film for 30 min, but I think 20 min would work just as well.
Key things to bear in mind are:
(1) Use as much mint as you can, 100 g is more than you think.
(2) if all you have is sodium bicarbonate, heat that up in a 375 °F oven for an hour to convert it to the carbonate. By the way, if the temperature decreases when you add your washing soda to water, it means you have a hydrate of sodium carbonate. If the temperature increases, that means you do not have a hydrate (you have plain old sodium carbonate). If you have one of the hydrates, you'll need to increase the amount of soda you add. Ah, chemistry!
(3) Try to avoid vitamin C with a lot of additives.
(4) Do some research. There are several people out there already doing good work in this area.
