Unicolor C41 1-Liter Kit - Life?
I've done a search through the forums through 15 pages and did not locate an answer. As I am new to the at-home C41 development process, I would like to learn some best practices and then some actual practices when it comes to using this kit.
Firstly, the supplied instructions state that 8 120 rolls can be safely developed in the chemicals. However, a search on flickr seems to have a consensus of 3 times this amount (24 rolls) can be developed with this kit prior to exhaustion.
Secondly, what does exhaustion look like? What effects become apparent on the developed negatives?
Thirdly, can I transition this exhausted chemistry to cross-processing duty, as color integrity (which I assume is the first effect upon exhaustion) is not important?
I would appreciate any additional words of wisdom that I may have failed to ask or be aware of. Thanks!!
This seems to be the current thread:
My previous 1L kit lasted for 24 rolls over 4 months. After I'd done 12 rolls or so, I started doing a clip test prior to each roll. On the 23rd and 24th rolls the clip was getting a lower d-max than before so I knew the end was near and the clip test prior to the 25th roll showed very low d-max so I stopped using it and mixed up a fresh batch. The last rolls really look about as good as the first rolls, perhaps a bit grainier, perhaps a little bit less contrast but it is hard to say with differences in exposure and equipment and film.
That fresh batch has now done 15 rolls in a month or so. The last roll was a 2 stop push (new Portra 400 @1600) so I hope I didn't kill the batch but will definitely clip test it before my next roll (been living dangerously with this kit, didn't clip test it prior to rolls 13, 14 or 15). I still have another 4 1L kits ready to go but may see if I can get some Kodak Flexicolor once I'm through them to see if it works any better.
Once the developer is completely exhausted I don't think even cross processing would work. Any rolls after 12 are bonus rolls really as 12 is already 150% of capacity according to the manufacturer. Perhaps after 8 rolls you shouldn't use it for anything 'serious' though I always find it odd, what pictures don't you care about? I'd be sad to lose just about any pictures I took as I took the time to take them so I obviously wanted that picture.
Are you cross processing E6?
As for best practices, heat the solution to 39C, use a simple bucket water bath to keep the temperature relatively constant and you'll be fine. I store the chemicals in a root cellar when not in use, not sure if that helps the life or not but I do it anyways.
Don't mix them up, keep your glasswear clean especially the developer as you can kill it by mixing it up with the blix.
Hope you didn't toss it out because you had no more films to process! It keeps well. Just did rolls 16-19 (new Portra 160 120, 2x new Portra 400 120 @400, new Portra 400 120 @1600 two stop push) on my current 1L kit which has been mixed for a while. Did a clip test before the roll of Portra 160 and it looked good so off I went. I even did the two rolls of Portra 400 @400 in the same tank since I somehow still had 1L solutions after doing 16 rolls! On my last 1L I'd already lost a lot of blix by now so was just doing single 120 rolls at a time.
Thanks for the feedback.
I'm not familiar with the clip test as it pertains to C41 and E6 processing. I'm assuming that you are checking the fix to make certain it clears the film base? Or is there a clip test where the developer is also tested?
Two kinds of clip tests can be done.
1) Developed in light, just like B&W. Put a scrap of film in the developer at temperature for the correct time. Then bleach and fix for the correct time at correct temperature. Compare to leader from previously developed film for D-max (developer) and clarity (blix).
2) Better, developed in the tank. Using film like Fuji Superia which has red, green and blue edge markings. Even if you don't shoot 35mm, buy some Superia at the drugstore and use it just for clip tests. Develop in a tank at proper temperature and for proper time, blix for proper time at correct temp. Use a 135 leader so you get some D-max in the exposed section and use some unexposed film to check the color in the edge markings and the clarity of the film for blix.
When D-max is low/thin or clearing shows a problem (redder than usual, etc.), dispose of the chemicals (properly) and mix up a new batch. In my experience the developer goes first.
Last edited by hpulley; 06-04-2011 at 05:16 AM. Click to view previous post history.
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
I mixed up a batch on 10 Nov 2010 and discarded it in March 2011 after 16 rolls. I don't print RA4 (yet) just scan, where colour shift is not critical and can easily be corrected.