How to judge C-41 processing result

RPC said:

I don't know how you got that from what I said. I said you adjust the results with agitation rates for each agitation type, with standard time of 3'15".

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In which case I do not understand what you said at all Can you provide answers to the points I made Currently all you have done is to repeat what you said earlier. The above statement tells me nothing unless it is accompanied with statements about how this translates into changes needed when moving to inversion agitation from continuous agitation

Let me make it simpler. Have you done both continuous rotary processing and inversion agitation? If so what specific changes did you make to the inversion times to ensure that both sets of negs were developed to the same standard?

pentaxuser

pentaxuser said:

Let me make it simpler. Have you done both continuous rotary processing and inversion agitation? If so what specific changes did you make to the inversion times to ensure that both sets of negs were developed to the same standard?

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You don't change the times. If necessary, you change characteristics of the agitation.
There is a reasonably wide range of agitation characteristics with both approaches that should give you the same results.

Pentaxuser,

You don't change the development time.

With inversion, you can adjust the number of inversions, and times in between to change results.

With rotary, you can adjust the speed to change results.

With any agitation method, you should run tests to get optimum results. Consult the literature as a starting guide.

There, I hope that helps because I am done here.

pentaxuser said:

Let me make it simpler. Have you done both continuous rotary processing and inversion agitation? If so what specific changes did you make to the inversion times to ensure that both sets of negs were developed to the same standard?

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I was not on the receiving end of this question but I can answer it very directly. Yes, I have done both intermittent and continuous/rotary agitation for C-41 process. My chemistry of choice was Kodak Flexicolor, and I used the standard C-41 temperature and times: 3:15 for developer at 37.8C, and 6:30 for bleach and fixer. I used film processors for both agitation styles:

1. For intermittent agitation I used the Heiland TAS. 30 seconds at first, then 3 inversions+rotations every 30 seconds [1].
2. For rotary, I used JOBOs and SST4, both at various speeds.

The results were verified with control strips and a color densitometer. Both were within spec. I did not have to make any changes to duration or temperature. I found rotary agitation to produce more consistent results. Intermittent agitation sometimes would leave a bit of faint surge marks near the holes on 35mm film, but very rarely, just on a few negatives out of 4 rolls in a tank. I gave up chasing them and simply switched to rotary.

[1] As recommended by the Kodak's CIS-211 document describing Flexicolor usage in small tanks at home.

@mtjade2007 thanks for sharing your views; I think we have a similar attitude when it comes to the technical side of photography. I.e. lots of interest and willingness to explore, but in the end fairly pragmatic. Would that sum it up for you as well?

mtjade2007 said:

One can agitate the film aggressively or moderately thus the oxidation of the developer varies dynamically. HAS provides a long term protection to the developer when it is in the state of storage in the bottle. That is static. I apologize if I don't use the word appropriately.

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Alright, I see, but I don't think that's the way it works, really. However, I'm not aware of research (it must be there) that has actually determined the kinetics of HAS in its antioxidant role. Do you have concrete information that supports the ineffectiveness of HAS at a short timescale? Give the mobility of ions in an agitated, watery solution at around 100F, this sounds very counterintuitive indeed.

PS: @mtjade2007 if you want me to split off the parallel discussion about agitation, let me know. It's kind of disjunct from your actual question, at least in how it progressed. If you're fine with it remaining in this thread, that's OK too.

koraks said:

@mtjade2007 thanks for sharing your views; I think we have a similar attitude when it comes to the technical side of photography. I.e. lots of interest and willingness to explore, but in the end fairly pragmatic. Would that sum it up for you as well?

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Koraks, I really appreciate your time in responding to my post. I am aware you spent a lot of time in the discussion with me patiently. I believe I do understand well of what you shared. I also hope you understand what I was pursuing on this thread. Thank you.

koraks said:

Alright, I see, but I don't think that's the way it works, really. However, I'm not aware of research (it must be there) that has actually determined the kinetics of HAS in its antioxidant role. Do you have concrete information that supports the ineffectiveness of HAS at a short timescale? Give the mobility of ions in an agitated, watery solution at around 100F, this sounds very counterintuitive indeed.

PS: @mtjade2007 if you want me to split off the parallel discussion about agitation, let me know. It's kind of disjunct from your actual question, at least in how it progressed. If you're fine with it remaining in this thread, that's OK too.

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There is really no need to discuss further of the agitation topic. The agitation by my JOBO is pretty constant. I don't see any problem for me to be concerned. The only thing I noticed is my developer is always short lived once it is used once. I could reuse it shortly after the first use. I toss it after 3 days. I also noticed the processing capacity seems lower than reports in this forum. It could be a result of constant drum rotation. It also could be my developer being nonstandard. I always replaced part C bottle with CD-4 powder.

Steven Lee said:

I was not on the receiving end of this question but I can answer it very directly. Yes, I have done both intermittent and continuous/rotary agitation for C-41 process. My chemistry of choice was Kodak Flexicolor, and I used the standard C-41 temperature and times: 3:15 for developer at 37.8C, and 6:30 for bleach and fixer. I used film processors for both agitation styles:

1. For intermittent agitation I used the Heiland TAS. 30 seconds at first, then 3 inversions+rotations every 30 seconds [1].
2. For rotary, I used JOBOs and SST4, both at various speeds.

The results were verified with control strips and a color densitometer. Both were within spec. I did not have to make any changes to duration or temperature. I found rotary agitation to produce more consistent results. Intermittent agitation sometimes would leave a bit of faint surge marks near the holes on 35mm film, but very rarely, just on a few negatives out of 4 rolls in a tank. I gave up chasing them and simply switched to rotary.

[1] As recommended by the Kodak's CIS-211 document describing Flexicolor usage in small tanks at home.

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Thanks for some specifics based on your experience, Steven. So, as I said when I asked the questions it would seem that for C41 quite a large range of inversion regimes produces the same end product. Yet it is not the same for b&w where a 15% reduction is recommended

I wonder why this is? Is it simply that over as short a time as 3 mins 15 sec the difference in the two regimes ( inversion v continuous rotary) is negligible but over the much longer times for most b&w films such as 8 mins plus and in some case a lot more the difference begins to show itself?

As someone with no or only a little knowledge of photo chemistry that is what seems to be the obvious conclusion. However the "obvious" conclusion can often be wrong simply because there are more things at work either in terms of the film type or chemicals used than meets the eye

MattKing said:

You don't change the times. If necessary, you change characteristics of the agitation.
There is a reasonably wide range of agitation characteristics with both approaches that should give you the same results.

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OK, Matt. What are the agitation characteristics to give the same results? I may be reading more into these characteristics than you meant For instance you could invert continuously for the 3 mins 15 secs or intermittently but much more regularly than every 30 secs which given the number of inversions might well equate to the equivalent agitation of rotary processing over a short time of 3 mins 15 secs.

Here's what Ilford says: "With spiral tanks, invert the tank 4 times during the first 10 seconds, then invert a further 4 times during the first 10 seconds for each further minute"

So for instance would this be sufficient to equate to the same agitation over as short a period as 3 mins 15 secs as continuous rotary as I said above in my reply to Steven

As I hope you will see, I am trying to reconcile why Ilford say that up to a 15 % reduction in time is recommended for continuous rotary processing with the fact that for C41 this does not seem to apply?

The reconciliation may be as simple as the reason I suggested above

All I am looking for is confirmation. Steven's reply would see to go a long way to confirm this but I am less sure about yours


Thanks

pentaxuser

pentaxuser said:

Yet it is not the same for b&w where a 15% reduction is recommended

I wonder why this is? Is it simply that over as short a time as 3 mins 15 sec the difference in the two regimes ( inversion v continuous rotary) is negligible but over the much longer times for most b&w films such as 8 mins plus and in some case a lot more the difference begins to show itself?

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Actually, I think your hypothesis may be correct. There is simply not enough development time, just 2:30, for the difference in agitation to manifest itself. Also, 30 second intervals is a fairly aggressive intermittent agitation. Had I given it a full minute between inversions perhaps the results would have been different.

If you want to experiment (for fun and science!), look at Fomapan 100 in Ilfosol 3. This combination reminds me of C-41: if you cook it for 3:30 you will get a gentle mid/low contrast level. Expose a roll, cut it in half, and develop using continuous vs intermittent to spot the difference?

pentaxuser said:

As I hope you will see, I am trying to reconcile why Ilford say that up to a 15 % reduction in time is recommended for continuous rotary processing with the fact that for C41 this does not seem to apply?

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Ilford films don't have to worry about colour.
Black and white films and developers are designed to allow for adjustment of contrast through adjustment of development times. That variability is both desirable and designed in.
C-41 colour films have three different colour sensitive components that are designed so that particular densities and contrasts are achieved at one point in time, at one particular temperature. If you vary those, you get colour shifts and crossover, that result in lousy results.
The main function of agitation is simply to avoid localized exhaustion of chemicals. Past a certain point, increasing agitation doesn't have much affect on development.
The Ilford recommendation for a 15% reduction in times when switching from inversion to continuous rotary agitation isn't shared universally. For instance, Kodak recommends no change of development time with Tri-X in replenished X-Tol when using large tank with nitrogen burst vs. continuous rotary tube agitation.

Thanks Matt From the bulk of your reply I will conclude that my theory on inversion v continuous agitation resulting in the same level of development is OK for the short time of 3 mins 15 secs with C41 and try to remember to say this when a question of inversion rotation v continuous is asked in the future in respect of C41 development

pentaxuser

I have used the UniColor 1 liter kit in the Jobo processor many times without a problem. Judging the negative takes printing and I suggest if one finds it necessary to have a color chart in a corner of the photograph to help with the judging.

pentaxuser said:

Thanks Matt From the bulk of your reply I will conclude that my theory on inversion v continuous agitation resulting in the same level of development is OK for the short time of 3 mins 15 secs with C41 and try to remember to say this when a question of inversion rotation v continuous is asked in the future in respect of C41 development

pentaxuser

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C41 directions usually also include more inversions than their b&w counterparts usually do. Every 30 seconds instead of every minute in most press kit manuals.

The process is also designed with continuous agitation in mind since that's how it's going to be done in a commercial lab.

sillo said:

C41 directions usually also include more inversions than their b&w counterparts usually do. Every 30 seconds instead of every minute in most press kit manuals.

The process is also designed with continuous agitation in mind since that's how it's going to be done in a commercial lab.

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Thanks. It may be that more inversions are safer and yet the general consensus if there is such a thing on a forum is that the Ilford 10 secs inversion per minute is equivalent to the Kodak every 30 secs for up to 5 secs which is what C41 directions say. On the surface it would look as either agitation regime should work OK

Perhaps the secret is: If in doubt increase the inversion agitation a bit more

pentaxuser

pentaxuser said:

the general consensus if there is such a thing on a forum is that the Ilford 10 secs inversion per minute is equivalent to the Kodak every 30 secs for up to 5 secs

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Not sure where you gathered that consensus from. It doesn't seem appropriate to me.

pentaxuser said:

which is what C41 directions say.

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Really?

Manual Agitation—Use this type of agitation alone only if it provides satisfactory uniformity: Developer— 1. Immerse the rack fully into the developer. Rapidly tap it on the bottom of the tank to dislodge any air bubbles. Raise the rack until the bottom is out of the developer; then reimmerse it. Do this once. This requires 4 to 5 seconds. 2. After the initial agitation, let the rack sit for 10 seconds. Then lift it straight up until the bottom is just out of the developer solution. Reimmerse it without draining. Do this with an even, uniform motion, taking 2 to 3 seconds to complete it. Repeat this procedure once every 10 seconds (6 times per minute). 3. Ten seconds before the end of the development time, raise the rack, tilt it about 30 degrees toward one corner, and drain it for 10 seconds. Then move the rack into the bleach. This agitation procedure should produce satisfactory process control. However, if the contrast plots are slightly low, increase the frequency of agitation. If the plots are slightly high, reduce the frequency of agitation, but do not reduce the frequency to less than twice per minute.

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Source: https://imaging.kodakalaris.com/sites/default/files/wysiwyg/pro/chemistry/z131.pdf (page 3-3)

sillo's link is to a Kodak Current Information Summary ("CIS") document - CIS-211.
Here is an alternative link on Tim Gray's 125px.com: https://125px.com/docs/techpubs/kodak/cis211-2010_08.pdf