A friend of mine, Karl Abbott, has recently started developing his C‑41 film at home. He is using the Tetenal C‑41 Press Kit and in July he was gracious to let a roll of my 120 Portra 400 ride along in the tank. Below is a slideshow of photos I took during the development process.
The process was pretty straightforward — three solutions, try to keep cross-contamination to a minimum, etc. However, unlike my experiences with black and white tank development, the time/temp tolerances were quite slim. Additionally, the temperature required for the solutions was 30F+ higher so a water bath to keep the temperature in the tank steady is a requirement. All that said, with appropriate workspace layout and awareness of upcoming actions, the processing would be quite familiar to anyone who has done b/w at home.
As far as the cost benefit, it is infinitely more cost effective for home development once you have all the equipment. And even then, after a few developing sessions you can really start to see some cost savings using the Tetenal. I can get my 35mm developed for $2.20/roll here in Asheville (no idea what it will be Nashville, if available at all) but it is $7+ for 120. With the Tetenal, you can do 12+ rolls of 35mm, or 8+ 120 per kit. So at $20 per kit, you quickly get ahead cost-wise. The only thing is that the chemicals don’t last as long as some b/w once mixed, so having a large amount of film to process at once is best.
Thanks to Karl for sharing this process — please check out his website and follow him on Twitter @kabbottphoto.