weird c-41 control strip results in jobo

frotog · Feb 14, 2007

I'm afraid I have yet another post regarding my continuing foray into controlling the c41 process in a jobo. My interest in obtaining optimum results has kept me in my darkroom developing kodak 5" 35mm control strips in two different types of jobo drum - the 3006 series drum (strip is taped to wall of cylinder) and the 2523 two roll drum. I'd like to make sure that I've recognized and mastered all the various contingencies of this process before I start developing film that counts. So far the results are not too promising. The most discouraging results are in the HD-LD spread - it's way too wide and the red channel is weak compared to the green and blue. The following #'s are my latest results in r,g,b respectively (HD-LD differences from aim)..... .02, .15, .13. So nowhere in the family of bizarre plots in the kodak z manual do they show the green channel spiking in this way. In my tests (eight so far) this is not an anomaly. The green and blue channels are consistently high w/ the green densities being as great or greater than the blue. My dmin #'s look good (-.02, -.04, -.02) or so says the tech I spoke to at Kodak. He had the following suggestions; decrease agitation and check the bleach (possibly leuco cyan dye formation). I'm already down to rotation speed 3 on the jobo (the manual suggests '4' for 3000 series drums). I'll post my results for rotation speed '1' later on this afternoon. Re: bleach....purchased at B and H two months ago, no date code on bottle, label on back in spanish, made in Brazil stamped on back label...possibly ballast for half a year on a banana boat! Be wary of this if you're purchasing chem. from b & h! I ordered some fresh bleach from a minilab supply but now w/ this storm I probably won't see it for another week or so. In the meanwhile I'd love to hear some people's thoughts on this.....Has anyone else run control strip tests on their rotary processor?

Photo Engineer · Feb 14, 2007

I use high agitation for Jobo drums and it works for me.

But, it does not always work well for everyone.

Your results also suggest low temperature or underagitation. In that case, the cyan layer is underdeveloped. If that is due to underagitation, then the cyan layer is not putting out the DIR quantity required, and the magent overdevelops.

There might be some silver retention here as well. If the silver is colored slightly, then it might peak and give additional bias.

There are so many problems possible here, I could wear out a keyboard on them. Just kidding, but a lot of things come to mind.

PE

frotog · Feb 14, 2007

Thanks for your post PE! I'll follow your rec on this as the EK tech. did not have much experience troubleshooting rotary. I'm going to look at agitation since I'm confident I'm on target w/ the temperature. Perhaps the high water level of my bath (the opening of the "mouth" is dialed in at 9 o'clock) is causing drag on the 3000 tank and already lower than normal rotation speeds? Underagitation would also account for the underactive bleach and fix stages of my process thus the problem being compounded by silver retention. Besides, I'm not certain, but isn't c-41 bleach a rather robust chemical in terms of its shelf life in an unopened bottle? Even it comes from Brazil what are the possibilities of it going bad? When you write "high agitation" are you referring to the 'p' setting on the speed dial?

Photo Engineer · Feb 14, 2007

I use the high agitation on my Jobo, which is P and is recommended by Jobo due to the drag caused by a heavy drum filled with chemistry.

Bleach keeps well and has a lot of capacity.

Just make sure that the pH is about 6.5. Kodak even says that you can use a 2% acetic acid stop after the developer for up to 1 minute at 100F to protect the bleach and insure rapid cessation of development. See their web site for information.

PE

OldBikerPete · Feb 14, 2007

I've run control strips in my 2513(?) tank with a single 5x4 reel on my Jobo CPE-2. I used the high agitation setting. My densities were all within 0.05 of the reference.
I used home-mixed chems and the formulae posted elsewhere on this site.

frotog · Feb 15, 2007

ok...so I cranked up the rpm's to "p", changed my temp +.1 c, used a two step prewash to make sure I was up to 100 degrees f. (total 5 minutes), and added 30" to both the bleach stage and the fix stage.

5'...two step prewash
3:15...Flexicolor dev.
7'....Bleach iii
7'....Flexicolor fixer and replenisher (mixed for the working tank solution, not replenisher solution)
6'....Wash
1.5'....final rinse

The control strips from this recent batch yielded the most exaggerated example of the trends that I've been noticing all along....

Dmin -.03, -.04, .00
LD -.01, .03, -.02
HD-LD .06, .27, .19
Dmaxb-Yb .23

What's weird is that my control strips for the small 2 reel 35mm. tank are much more on point. Same chem., same batch of control strips, same drkrm., same speed on jobo ("p") and same batty operator. Check it out...

Dmin .01, -.03, .01
LD .01, .02, .01
HD-LD .02, .07, .02
Dmaxb-yb .03

Based on these results I'm thinking two things...the 3000 series drum is causing more agitation than the 2500 two reel and thus causing a spike in the green and blue readings (don't they move the fastest when over-developing?)....also, maybe the fixer working tank solution is too dilute for rotary processing, being approx. 85% the strength of the replenisher solution. IDK...maybe there's a problem w/ my rotary speeds, either too fast or too slow. I'll try it at a slower speed later on to compare results.

PE...is there a simple technique to check pH on my bleach? Also, not having any 2% acetic acid will Kodak indicator stop work ok?

Thanks for your help....I'd feel completely in the woods w/out this forum!

Photo Engineer · Feb 15, 2007

Overdevelopment affects Yellow and Magenta more than Cyan. This is correct. Overagitation does the same.

I'm at a loss to explain this.

Are these Kodak control strips? Have they been kept well? Are they out of date? I ask this to get more information.

A suggestion is this. Take a photo of a macbeth color checker and run through the process. Read the density of each step in the neutral step scale. Taking into account the offset introduced by the dmin, you should get 3 parallel lines if you plot step vs density. If this works, then the test strips are off, if you see the same magenta bias as you do in the test strips then something is seriously wrong here.

Yes, you can use Kodak indicator stop diluted as stated on the label.

PE

Nick Zentena · Feb 15, 2007

frotog said:
the 3006 series drum (strip is taped to wall of cylinder)

Is this causing problems? Chemicals not getting behind the film? Just guessing

frotog · Feb 15, 2007

Yes, Kodak control strips - the five inch 35mm kind. I've taped them to the inside of the barrel on the 3000 series drum. The first tests I ran were w/ recently expired strips (this month). To rule this factor out I purchased some fresh strips and alas, same trends as w/ the older strips.

If, overdevelopment and overagitation affect Yellow and Magenta dye layers more than the Cyan then I should try less agitation right? After all, the aforementioned results w/ the two reel are significantly closer to aim. The film in this tank is nearer the center of rotation and so less agitation than w/ the 3006 drum. Another consideration...perhaps the speed dial on my cpp is setting the rotation speeds faster than the factory presets.

I have an old xrite 810 and an equally old trans. calibration strip that's kind of scratched up w/ use. Am I correct in assuming that because I'm comparing deviations from measurements made from the reference strip and using the same machine to make all the measurements, the measuring device should not be an issue?

Unfortunately, no macbeth color checker but I do have the 14" Kodak color control patches as well the kodak gray scale that came w/ it. The color patches are laid out in two rows, a saturated row and a less saturated row of the same color on top, in bl.,cyan, green, yel., red, mag., followed by White, 3/color, and then Black. Would this work for the test you prescribed?

I'm waiting for a fresh stock of bleach and fix to arrive. I do have another developer kit I could stir up inorder to rule out faulty developer. Meanwhile, I'm ready to descend back into the saltmine for further testing at lower rotation speeds....

frotog · Feb 15, 2007

Nick - the emulsion side is facing out...does the acetate side need chemical activity? The strip is taped on either end leaving the long side pushed up against the wall of the drum so as to mimic the curl of a sheet of film. Also, I'm providing ample prewash time. However, in the test I'm about to run I'll let one of the control strips loose in the barrel of the 3006 just to make sure that this is not an issue.

Photo Engineer · Feb 15, 2007

I thought you said that the cyan was low and the other two were high. If that is the case then it is underdevelopment and/or underagitation, but if cyan is near normal and the others are high then it is overdevelopment due to overagitation.

Too much activity will affect the top two layers.

The back of the film does not need treatment, but Jobo has some provision, I believe, to allow the back to be wetted during the process. I use ribbed drums or reels.

PE

frotog · Feb 16, 2007

Most recent test w/ 3006 drum (w/ kodak indicator stop bath diluted quarter ounce to one quart to stop development and rule out developer carryover)...

****please note****readings are in r, g, b respectively....

dmin...-.04 -.02 -.02
LD...... .06 .13 .03
HD-LD.. .02 .18 .14
Dmaxb-Yel.b .21

Changes made to process include addition of 30" stop bath and slower agitation ('F') setting. At a development time of 3:15 the contrast is still too high. However, the dmin Green has finally fallen in line w/ the Blue for the first time in all of my tests w/ this particular drum. Could this be due to stopping the development stage w/ acetic acid?

I'm near the slow end of rotation speeds so I think I'll try knocking 15% off my development time and see how that affects the plot...Stay tuned...

frotog · Feb 16, 2007

Oh yeah, Nick...
In the last run I put a second control strip in a separate chamber of the drum and let it process loose in there. No differences between that strip and the one taped to the wall of the cylinder.

Photo Engineer · Feb 16, 2007

How does the strip look?

The strip should look decidedly magenta in neutral patches. Green patches should be weak and red and magenta patches should look abnormally bright. If scanned, this should show up as a greenish hue in the neutrals if correction is turned off.

This is just a double check. Otherwise, I have no clue.

PE

frotog · Feb 16, 2007

Here's a scan of the latest strip alongside the reference....

Photo Engineer · Feb 16, 2007

I ran the image through some tests in photo shop. It said and my eyes agreed, that the two images differ in that the one on the right has more overall cyan in it, or the one on the left has less cyan. Otherwise, they both seem to have a similar neutral scale.

Therefore, I would suggest trying to make a contact print of these two strips side by side and balance the neutral. I think you will find that they make identical neutrals at the same balance, but differ only in density. The one on the right will be about 0.1 darker in the print.

This is a guess and is provisional on the scanning process not having distorted the balance between the two significantly.

PE

frotog · Feb 16, 2007

Here's another scan of the same two strips....I left the color balance the same but changed white point and contrast so that it would be a bit more visible...To the naked eye the patches in the control strip look quite a bit more saturated than the control (this is the case w/ all the strips I've run regardless of agitation or time). Also, the film base appears more red in the reference (not the case in the other strips I've run at faster rpm and normal times) BTW, the control strip is from a 3' development at the slowest rpm on the machine.

It seems strange that the film base density on the control developed in the jobo appears significantly less dense than that of the reference.

Here's the results from the 3' run w/ slowest rotation speed...

dmin... -.04 -.04 -.02
LD... -.02 .05 -.03
HD-LD... -.03 .08 .06
Dmaxb-Yel.b... .02

Certainly closer to aim than the past runs but still exhibiting the same spike in the green, the weak red channel and the wide color balance spread of all the other tests I've run. All things point to developer being too active and possible weak bleach solution. The fresh batch of developer gives the same results as the first batch. Water quality should not be an issue since I'm using distilled water for the mix. Despite what it says for rotary processing in the z-manual, perhaps I need some starter to balance out the activity of this developer...

What's with the green!! Arghh!! Could a weak fix be causing this???

Photo Engineer · Feb 16, 2007

If density is lower in the dmin, then the process is what we call 'cool' which means underdevelopment, nothing more, but if contrast is high, or density is high, then it is 'hot'. This has elements of both.

I would stick by my suggestion above. Make one print at the same balance from both strips on one sheet of paper. I'll wager that they both look good except the test strip will be just a tad darker than the control.

PE

frotog · Feb 16, 2007

I'll take your advice and fire up the old fujimoto w/ fresh chemistry tomorrow. In the meantime it's Friday night and I'm turning off the phone, warming up some pizza and descending into the black room to continue chasing my elusive aim...

PE, your knowledge in all things silver fills me with awe.

frotog · Feb 20, 2007

o.k....
I've attached a side by side contact print of the two strips. As I expected, the control strip has a strong cyan cast especially apparent in the YEL. but also very apparent in the HD. This was printed at 50 points yellow, 40 points magenta.

I just received a fresh container of bleach. This bottle has a date code stamped on it. Perhaps I should try re-bleaching this control strip to see if that changes things.

frotog · Feb 20, 2007

I just finished re-bleaching the strip with bleach from the fresh kit. No difference. That rules out cyan-leuco dye problem...must be the developer. I think I'll try some of the flexicolor replenisher WITH the starter. Something tells me that this one gallon kit w/out the starter is the smoking gun...

Photo Engineer · Feb 20, 2007

Nope.

The scans look as if they differ in speed or density rather than color balance.

I cannot see a color balance difference in the posted pictures on my monitor. And, a C41 color developer (not developer replenisher) should not need starter.

BTW. these two samples are no where near balanced. The spots near the bottom should be both balanced to neutral. I would subtract about 20R for starters. I would also increase the exposure until the middle patch showed some density.

PE

frotog · Feb 21, 2007

Wait...the spots near the bottom should be neutral? Do you mean that the Yel. patches have too much cyan in the print and so I should add about 20 points red to the print? Other than the yellow patch which I assume should appear blue in the print, I have no idea what I'm aiming for in my print. I guess the dmax should appear paper white, right? And I'm guessing the LD patch should print ever so slightly lighter than dmin and thus determine my overall exposure. Please advise.

Photo Engineer · Feb 21, 2007

The Kodak control strip is a neutrally balanced step. Your samples are both slightly overexposed and too cyan. You should see a white spot and grey spot and black spot. Not several white and one cyan.

The bottom spot is labeled "Y". So this should be pure blue, not cyan. I may have over estimated the amount of 'red' to change the pack by, but that might be due to the slight overexposure.

I think that the point is that both of these printed nearly identical, and not far out as your measurment indicated. Reprint with less exposure to lighten slighlty and reevaluate the bottom spot for being blue or cyan. That is what I'm trying to say.

PE

Photo Engineer · Feb 21, 2007

My advice above contains a typo. I meant UNDEREXPOSED.

The neutrals should display one BLACK step, one GREY step, one light GRAY step and one CLEAR step. The patch should be pure BLUE with no hint of a cyanish tint to it.

Yours appears to have two white or clear steps.

Apologies.

PE

weird c-41 control strip results in jobo

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