What you’ll see he does is makes the film negative, then tapes it down to a piece of glass or plastic to hold it in place. He then uses toilet bowl cleaner with bleach to recover the negative. He rubs it on until the black dark area comes off. Then when it’s satisfactory, he carefully washes the negative.
This process is called a bleach bypass–and it’s a beautiful process that creates more muted tones. In this video above, another photographer shows a much more complicated process involving a pump and water/bleach being recycled. He’s also sure to get rid of the goo that comes with this film very carefully.
It’s fun stuff and goes to show you can easily get a 3×4 inch negative–which is pretty large. It’s far larger than 35mm, 645, and even 6×7. Then when you scan the image and reverse it, you tend to get something sharper than what the positive print is.
Unfortunately, Fujifilm discontinued Fujifilm 100-C film, and so it’s becoming tougher to get your hands on. But if you manage to get some, you’ll see you get 10 shots–which gives you 10 positive prints and 10 negatives. These are also a whole lot easier to work with and develop than needing to go into a darkroom because the entire development process takes place with all the chemicals in the shot. These chemicals go through print as it ejects from the roller.
This doesn’t happen with more modern day Instax and Impossible film because you only get the positive print. It only happens with peel apart film.