Questions about Fuji X-Press C-41 kit

[grainyvision]

I've searched, but not found any good answers for these. So, I just bought and mixed a 1L batch of this kit. I have some questions:

* What the hell is the recommended agitation of this? There seems to be a translation error where it says something like "After initial agitation, put tank in water bath for 13 seconds, then remove and agitate for 2 seconds. Repeat this process for 10 seconds before the last 10 seconds of the process. Then, drain the tank for 10 seconds".. When I translated the french instructions to english, it seemed to say "repeat this process, UNTIL the last 10 seconds of the process, and then drain"... What is everyone else with this kit doing?
* What kind of shelf life can I expect out of the concentrates? Their instructions seem to imply they can be stored safely for some amount of time, but I've seen mixed reports. The weak link appears to be part C of the developer. No one seems to give specifics about how long it takes, but eventually this will oxidize and turn into black sludge. I'm curious how long this takes, weeks, months? Also, there is at least one post I read of someone making a big batch, dividing into 5 1L bottles, and then freezing the 4 bottles he wasn't yet using, which caused them to last for more than 1 year. Standard (<5C) refrigeration allowed it to last at least 6 months. Has anyone else done this? I've heard freezing chemicals causes precipitation and tons of problems, so I'm not sure I trust that report too much.
* Is it really necessary to do a 3 minute and 30 second rinse between bleach and fix? Is there that much risk of the fixer getting contaminated otherwise?
* Do you really do the "vigorous" agitation of 1 complete inversion (I assume upside down, then right side up) per 1 second? It seems very rapid to me
* Why should the water bath be 102F if the developer should be 100F? Did I misread the instructions?
* Not about the kit, but if I wanted to do bleach bypass, could I change my mind and bleach and re-fix if I don't like the results?

 

[mnemosyne]

• agitation: yes, the description is confusing: What they mean is: invert constantly for the first 30 seconds, then 2 very quick inversions (one second each) every 15 seconds. At 10 seconds to the end of your processing time, start to drain the tank. The Kodak recommended scheme for hand development in inversion tanks is basically the same, but they only require one inversion every 15 s. I always sticked to the slower Kodak scheme and did not have any problems.
• when I used the Fuji kit I kept the whole 5 liter batch of developer in a wine bag (bag in box system) and had no problems to keep the stuff fresh for 6 months. I did not go bad after that, it is just that my self set limit of use was reached and I discarded
• bleach and fix has double capacity of the developer, so normally you reuse them. This is why you want to reduce carryover of Bleach into Fix, any contamination can possibly accelerate deterioration of the fix
• temperature: No you did not misread the instructions: The temperature of the water bath must be above the process temperature to compensate for the enevitable loss of heat during the agitation cycles. Also, my experience showed me that the preheat temperature of the developer has to be higher than process temperature, because the solution will lose quite a bit of temperature while you pour it into the tank. Just how much has to be determined by trial and error (see below)
• I recommend the following procedure to dial in processing temperature: Do a test run with your normal tank ,reels and so on but without film and with water instead of the developer. Preheat the tank for several minutes (the longer the better) in a water bath that is approximately 41C at the begining. let the water bath cool down until it reaches 38.5C, now the tank and the bath are ready for processing; in the meanwhile you have preheated your developer solution to the same 38.5C (again its usually easier to heat it up to say 40C and then let it cool down slowly to the target temperature). When both the developer solution and the water bath have reached 38.5 C you quickly pour the "developer" into the tank and do your initial 30 seconds of agitation, then place the tank in the water bath and quickly pull the lid. Do a quick measurement with a digital thermometer. Replace the lid. Continue normal processing scheme. At 3 m 05 s (the point you would normally drain) pull the lid again and do a second measurement. The first measurement (after 30 seconds) will tell you if the preheat T of the developer was correct. If the T is too low, set preheat T aim higher and vice versa. If the second measurement (at 3'05") is dead on or slightly off target (+/- 0.15 C) you are good to go. If the T is too high you have to lower the T of the water jacket and vice versa. This should get you in the ballpark. To facilitate things you should use a digital thermometer that reads out quickly but the cheap ones are not very accurate in my experience, so it should be calibrated against a known good high quality thermometer.

 

[grainyvision]

Do you have a good thermometer recommendation? I have a slow glass tube one that seems very accurate, but very slow. Then I have some fast read dial ones and some digital, and for the hell of it even tried a medical thermometer... all of them seemed to give results that were different by around 0.5C, with some outliers being 1-2C (dial thermometers are terrible apparently?)

 

[MattKing]

Use your slow glass thermometer to check the fast digital ones regularly. Make sure the check is at the temperature you are aiming for. Then use the fast thermometers when you process.
You may need to incorporate a small offset from the digital thermometers reading,, but as long as you keep that update current, it is easy to do.