Any tips for C-41 in a Jobo?

erikg · May 28, 2010

I'm going to process some C-41 films in my jobo using the Tetenal kit this weekend. It's been years since I've run color. I didn't have the jobo back then either. (CPP) I'm running 120 and 4x5. Should I presoak? Is 100 degrees the best? Any other advice that I won't get from reading the manuals?

Thanks!

erik

DanielStone · May 28, 2010

Pre-Heat, don't pre-soak. Run the loaded tank in the water jacket for 10-15 min to get it warmed up, and make sure your chems are tempered well, and stay at a stable temperature.

38deg C(100F) is what c-41(at least the Kodak and Fuji chems) are designed to be run at.

-Dan

anikin · May 28, 2010

Jobo makes C-41 a pure pleasure. I pre-soak for C-41 and pre-heat only for E-6. Excellent results either way. I was getting drying spots with Tetenal's stabilizer, so you may want to try it on junk negatives first. Switching to Kodak's final rinse solved it. Have fun!

Photo Engineer · May 28, 2010

Pre-soak, don't pre-heat. An empty drum requires a lower level of water in the water bath to prevent "flotation" due to buoyancy and thus the drum often does not keep warm unless extra water is added later when in use. Also, if the drum does "float" a bit, it stresses the red gasket at the top of the tank near the cog if you have a lift.

In addition, the core of the drum does not fully heat with just air which has poor conductivity.

The pre-wet does the job rapidly, and also helps prevent air bubbles. It also aids in rapid wetting of the film with developer.

PE

guyjr · May 28, 2010

I've been using the liquid Tetenal kit for six months now, and I've gotten good, repeatable results by sticking with a 5 minute warm up of the tank once film is loaded, no wetting. Make sure the motor is running too of course.

Then, stick with exactly what is printed in the Tetenal instructions - 3:15 I believe for dev, 4:00 for bleach / fix, and then 4:00 or so for rinsing (I do 6 changes of water - 4 every :30, then 2 more every 1:00). Then I do one more fill with water, add the stabilizer, manually rotate off the Jobo for 1:00, pull and hang to dry.

guyjr · May 28, 2010

So P.E... can I ask... does the pre-wet affect the development of the film at all? I actually do a pre-wet when I develop black & white, because that way I can stick with the exact timings listed on the Massive Dev Chart. But, I notice that there's an awful lot of "stuff" which comes out of the tank when I dump the pre-wet water, and I wonder if that has any effect on the development of the film? Would I expect to see the same change of color of the water when pre-wetting color negative film, and if so, does that impact the timing of development from what is published?

Thanks for your help!

Photo Engineer · May 28, 2010

I use the prewet all of the time and have for over 20 years. I have seen no significant difference in the few tests I did run.

I have done it both ways though, over the years and find better uniformity and fewer defects using a prewet.

The colored materials that wash out in a prewet have been described elsewhere in a lengthy thread, but basically they do no harm by being washed out.

Two things to remember. I discard my developer after use. I have tried reusing the developer and found it unsatisfactory to me and that is why. I also use 2 prewets of 30" each as the first one drops in temp quite quickly.

Also, the 4' wash time is probably not enough. If the stabilizer or final rinse (which I reuse) gradually turns light pink, the blix is getting into it through a poor wash and will eventually harm the film.

PE

erikg · May 28, 2010

Thank you everyone. This is very helpful. I no longer have a pro lab near by to get quick turn around, so if I can get this down it will extend my ability to shoot film on certain jobs into the future. Seems like it wasn't so long ago we had 4 labs to choose from. There is still a good lab in the Boston area I use, but often I need faster turn around, especially over a long weekend. I appreciate all of your input.

guyjr · May 28, 2010

Thanks for the info PE, I was using a 5 minute pre-wet with the b&w... I'll try the shorter ones with color (on a test roll) and see how it goes.

mtjade2007 · May 29, 2010

Photo Engineer said:
I also use 2 prewets of 30" each as the first one drops in temp quite quickly.

PE

Great tip, PE. This makes a lot of sense. The temperature can really drop quite a bit with only one prewet, especially if there is a lot of films in the tank such as a roll of 220 film. When I develop manually my prewet water used to be tempered at 105 degree. There was no need of two prewet. But with my Jobo ATL processor this is impossible. It can only be set to whatever the process is set to tempered at, which is usually 100 degree of course. I measured the temperature of the prewet water when it is drained out of the tank. It was usually 2 to 3 degrees lower than 100. Before the developer is poured into the tank the film inside could drop a few more degree again. It really could cause under development as a result.

Photo Engineer · May 29, 2010

The drop in prewet temp has probably been the source of some of the "mythos" about prewet problems. If you have a drop, then you lose density in the upper scale. You then conclude erroniously that a prewet is bad.

PE

OldBikerPete · May 29, 2010

I don't know if it is still the case with modern emulsions but E4 gelatin used to swell up considerably, opening 'pores' into which the developer can move. It is in order to allow this process to go to completion before the addition of chemicals that I run a pre-wet of 5min followed by another 30second wet before adding developer.
Peter.

Photo Engineer · May 29, 2010

E4 used a prehardening step. Even so, it was much softer than E6 or C41 films which both can be run at 100F.

I never ran E4 in a Jobo, only in a SS tank.

PE

erikg · May 30, 2010

I'm in the color processing business now folks. Thanks for all the help. I followed PE's advice and did the 2 prewet baths, so far so good! Fun to do something new.

schlger · Jun 1, 2010

My fix comes out sgnificantly pink. That pink disappears after about one day. The wash water is also pink, if I let rest the film some time in a water filled drum even after 8 min washing in the Jobo Autolab. I made the same experience with E-6 (Fuji Provia F) and B+W (TMY) in all cases the wash water stays absolutely clear after a washing time of about 20 - 30 min. Does that pink come from the senzitation dye? Could it come from exhaustet fix: I experience a longer need for washing, when the fix is used several times in B+W. But for C-41 I use the fix only one shot for 5 films per liter. can I overwash C-41 film?

Photo Engineer · Jun 1, 2010

If the wash is pink or the fix is pink in E6 or C41, this indicates the presence of bleach and thus washing is not complete.

The wash after the bleach must NOT be pink. If the stabilzer/final rinse is pink, this is bad!

PE

Tom Taylor · Jun 1, 2010

Both Kodak and Jobo advise against using a pre-wet with C-41. At best, you'll simply be diluting the developer.

Photo Engineer · Jun 1, 2010

Tom Taylor said:
Both Kodak and Jobo advise against using a pre-wet with C-41. At best, you'll simply be diluting the developer.

Tom;

Sorry, but I must disagree. It does not hurt if done correctly. AAMOF, my Jobo books suggest using one.

PE

anikin · Jun 1, 2010

PE,

What about E-6? Is it OK to use pre-wet with it? First few times doing Kodak film I got slides what were a bit too dark which seems to indicate under-development. Funny, but Provia that I developed in the same tank, came out good. I am thinking of trying pre-wet with E-6 to get better temperature consistency, but wanted to check if that might cause problems.

Eugene.

Photo Engineer · Jun 1, 2010

I have not run any E6 in my Jobo. I have sent it all out. So, I cannot help. Are you sure that you are using the right first developer time? Both Kodak and Fuji suggest different times.

As for C41, I use 2 30" 100F prewets, I fill with developer after the dump and complete drain of the prewet, and start the timer and use 8" to drain the developer such at 3'15" are the total time. Incomplete tempering or incomplete drain of the prewet will cause problems as will long times in the prewet.

PE

anikin · Jun 2, 2010

PE,

It is possible the wrong 1st developer time (6:30) could have been a culprit. Kodak's E-6 chemistry docs are rather vague on that topic, they state 6-7min 1st developer time. So I suppose, if one roll's preferred time was closer to 6 min and another closer to 7 min, that would account for the differences. However, I find it hard to believe that commercial labs change 1'st developer time from one roll to another based on film manufacturer.

I suspect it's more likely that temperature of my 1st developer dropped too low and E200G was just a bit more sensitive to it than Provia. I was hoping that using pre-wet would give me more stable 1st developer temperature, but Kodak's documentation strongly suggest not using it. Anyway, thanks for the suggestions!

Eugene.

Photo Engineer · Jun 2, 2010

Eugene;

Please go here: http://www.kodak.com/global/plugins/acrobat/en/service/Zmanuals/z119-10.pdf

Most everything you need to know is there including prewet information for E6. Go here: http://www.kodak.com/global/plugins/acrobat/en/service/Zmanuals/z131_03.pdf for C41 information.

The prewet is not mentioned AFAIK in the C41 but is for E6.

There are conflicts between E6 and C41 regarding using a prewet. I have used it in C41 for years with no problem and find the films that I use to be virtually insensitive to prewets of 1 - 2 minutes.

PE

anikin · Jun 2, 2010

PE,

It explains a lot.

This is a different document from what I've been looking at. The one I used for reference was "KODAK PROFESSIONAL Single-Use Chemistry Kit" http://www.kodak.com/global/en/professional/support/techPubs/ti2443/ti2443.pdf

I think I'll try pre-wet next time I run E-6. And z119-10 document recommends 7min development, so it looks like my slides were slightly under-developed.

Thank you Ron!

Photo Engineer · Jun 2, 2010

Under the circumstances, with the longer development time of E6, a prewet is probably less important in terms of uniformity and tempering. The short development times of C41 though can cause uniformity and bubble (pinhole) problems without a prewet.

I have observed a tiny loss in contrast in C41 if I use a very long prewet, say > 5 minutes. I did this once when the temperature dropped in my sink, so the temps went down a bit and I had to hold the process to get things back up to normal.

So, I would guess that the prewet is more useful in C41 than in E6, but that is just a guess based on development times and therefore the development activity.

PE

frotog · Jun 2, 2010

Controlling temp within a 1/2 of a degree f., which IIRC is kodaks spec on this, is critical for the c-41 process to be truly in control. The small volumes of chemistry used and temperature drop upon entry and over duration of process stacks the odds against successfully producing in-control processing in the jobo. Another problem with the jobo is oxidation which occurs even more rapidly with the small volumes typically used in home processing.

That's the bad news... the good news is that none of this will matter (assuming you've got your technique figured out) unless you're the kind of control-freak who'd laboriously plot control strip after control strip to ascertain in-control process. Contemporary c-41 and ra-4 seem to be very forgiving (thanks PE!) as I made acceptable, if not respectable, prints from test negatives processed with control strips that, when plotted, evidenced a process that was not in-control.

As for the pre-wash vs. no pre-wash debate... Thanks to a lightening fast thermocouple thermometer I honed my technique both with and without a prewash. After doing numerous runs both ways and recording the results of the test strips I was able to conclude for myself that it did not make a difference dry or wet (except that preheating in the manner PE describes is simpler than working with a hairdryer).

I went through two boxes of control strips before I figured out the gremlin in my process. Now it's in-control so long as I run a nitrogen feed during development. Processed in this manner my negs are totally clean, with even, mottle-free blue skys. Show me a pro-lab that can do that for less than $8 a sheet (i.e. LTI "special process")!

Any tips for C-41 in a Jobo?

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