c41 processing in a home darkroom

Discussion in 'Film and Processing' started by dale_weiss, Oct 14, 2010.

  1. I am just wondering if anyone out there is set up for c41 in their home darkroom. I am thinking about it, but would like to know what is involved equipment wise and can it be done.
  2. If you are set up to do B&W, you're all set for C-41. You need different chemistry of course, and you need to control the temperature more closely. 100F or 38C +/- 1/2 degree. After that, it's a lead pipe cinch.
  3. C41 easily doable, but RA4 harder.
  4. Your only problem is the developing temperature 37,8C +/- 0,5C.
    A simple and effective processor is the Jobo CPE/CPA or CPP. Especially with elevator suitable for the short C41 CD time of 3:15 minutes.
    With a 2523 tank suitable for 2x 135-36, 2x 120/127 or a 220 roll film. 270ml fluid in rotation.
  5. I develop at room temperature. It's longer and because "room temp" is more stable, I get better results. I have yet to see any difference in my results.
  6. Peter: What development times do you use at 68deg for developing color film?
  7. 18 for the dev, 8 for the blix, everything else normal.
  8. Being able to get good results at room temp. encourages me to try it sometime. I was always put off by the excessive talk about the necessity of absolute temp (@100 degF) and time control in the c-41 process. With bw I can be (and have been) off as much as 10 sec. and +/- 1 degree F and still get excellent results and with t-max film too. (The reputed difficulty developing the oh-so-sensitive t-max is mostly nonsense imo.)
  9. Yes, it does give a lot of latitude in the development process. Just remember to keep everything at the same temp, even the presoak and wash. I keep jugs of water hanging around, for this reason.
  10. I process c41 at home as well and have had good results... I just bought a ~$15 crockpot from target and use that to warm a water bath with the chemicals in it. I'm not setup to print color (I scan and print via inkjet), so it's possible that my process isn't controlled enough for traditional printing and produces color shifts that would be impossible to correct, but if there are such shifts, my scanning software and lightroom take care of them pretty much automatically.
  11. Dale,
    I use the Unicolor kit at 100 degrees with very consistant results. My water bath is thermostatically controlled, and I add 5 seconds to the development time per roll of film. I easily get twice the number of rolls the instructions recommend, and the chemicals last for months in full bottles.
    Did you work out your own development times? What chems do you use?
  12. What would be the symptom of poor temperature control e.g out by a degree or two ? Would you have to throw away the film , do you get color casts etc. Im thinking about it , not to save money but time.
  13. For all practical purposes, degree or two off will not be a problem. You may get slight over/under development and a tiny bit of color cross-over. Just like with B/W, it's not a matter of absolute value, but a matter of consistency from run to run. If you take your film to a drug store, you are likely to get results that are worse because of stale chemistry, unmaintained machine etc. Basically, without thermostatically controlled temperature, you need to use water bath. Start processing at temperature a degree or two above recommended temperature. By the time you are finished it will be a bit below, and on average you'll get the desired result. If you do it this way, the results will be spot on. Also, two 30 second pre-soaks with water of correct temperature before development are highly recommended.
  14. Slight shifts in negatives lead to larger swings in filtration when printing RA4. Consistent color leads to easy printing with repeatable results. I've never had much of a problem printing RA4 from self-processed C41 using a JOBO.
    It's easy to imagine, however, a scenario without the JOBO (or without similarly close temperature control) and of having to dial in vastly different enlarger filtration for every processing batch, or having scans that are all over the place, and not profile-able. This could either waste a lot of materials and/or time.

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