Quick C41 chemical test

elerion · Mar 23, 2017

I reciently lost a roll I developed on C41 gone bad. It came out totally transparent, by the action of the blix on the undeveloped film I suppose.

I made fresh developer from an opened concentrate, and it works great again. But I will like to know if there's a quick way to test if the developer still works, not requiring to go through all steps with a test strip (it takes quite a long time heating and doing all manually), neither loosing a full roll again

Thanks!

bvy · Mar 23, 2017

Take an unexposed piece of color negative film (like the leader/tongue) and drop it into your room temperature developer. It should turn black after about five minutes.

Rudeofus · Mar 23, 2017

bvy said:
Take an unexposed piece of color negative film (like the leader/tongue) and drop it into your room temperature developer. It should turn black after about five minutes.

The idea is to do this in broad daylight, such that development action on a fully exposed test clip can be observed. There is no requirement that this test clip is unexposed before the test.

bvy · Mar 23, 2017

Rudeofus said:
The idea is to do this in broad daylight, such that development action on a fully exposed test clip can be observed. There is no requirement that this test clip is unexposed before the test.

I meant "unexposed" in the sense that it hasn't been fully developed. Clip the tongue from a roll of fresh film, or exposed (undeveloped) film, and do the test in full light. Sorry for the confusion.

elerion · Mar 24, 2017

Thank you. It's clear now.
I wonder how I didn't think about it!

elerion · Apr 21, 2017

It worked great, as expected.
More than 5 minutes were needed, though.
Tetenal C41 required about 9 minutes for me (at about 22ºC ambient temp).
The films I developed right after the test came out perfect.

BMbikerider · Apr 21, 2017

Can I suggest a simpler method? If you have used the developer once and stored it afterwards for another film, if the developer has darkened past a pale yellow colour then ditch it. The same applies to fresh unused developer. Or as I do use once, and throw away. It never fails and completly avoids a film loss.

At todays prices developer is cheaper than film.

elerion · Apr 21, 2017

BMbikerider said:
Can I suggest a simpler method?

Sure, thanks.

Even though cheaper than film, C41 and RA4 chemicals are not that cheap.
Not reusing C41 would increase cost by 25-50% over that of the film. Too much for me.
I do use RA4 single shot, but that's because I use drums, and I always almost exhaust the chemicals at the end of the session.
The important thing here is avoid air getting in the concentrate bottles.

Rudeofus · Apr 21, 2017

I recommend you record the time needed by working C-41 CD to blacken test clips at room temperature. Given enough time, even completely exhausted C-41 CD will eventually darken test clips, this is not an on/off change like with Ascorbate based B&W developers. If the time needed for comparable blackening increases to seven minutes before the next run, either throw out the C-41 CD, or run an uncritical piece of film and record the results. This will eventually give a a useful threshold time beyond which you can't get usable negs any more.

Gerald C Koch · Apr 21, 2017

Probably the easiest thing to do is to follow the manufacturer's recommendations for storage life, capacity and proper storage. They should be given on the instruction sheet for any kits.

elerion · Apr 21, 2017

Good point.
You mean "increases to seven minutes" or "increases BY seven minutes"
It already took around 9 minutes.

It's true that the developer exhausts gradually with use (because there's a compensation when several films are developed).
but I thought it dies quite abruptly when oxidized.

pentaxuser · Apr 21, 2017

elerion said:
It worked great, as expected.
More than 5 minutes were needed, though.
Tetenal C41 required about 9 minutes for me (at about 22ºC ambient temp).
The films I developed right after the test came out perfect.

Not looking to start an argument about the inevitability of colour cross-over at less than 38 degrees C but assuming that the OP has been able to judge correctly that the film is perfect and given that Tetenal does gives times for a range of temps less than 38C then it raises the question of whether a temperature of less than 38C does (a) inevitably give colour problems or (b) sometimes gives problems or (c) simply increases the chances of problems which may or may not emerge.

If problems are likely then I have always been puzzled about why Tetenal gives a range of temps. Why would Tetenal gives a range of temps if there is a reasonable chance of problems which might cause users to move to another developer such as Kodak and cause it to lose business?

pentaxuser

Rudeofus · Apr 21, 2017

@pentaxuser: the 22°C number given by elerion referred to the test clip, not to the actual process run.

@elerion: if that test takes five minutes at the first try, and nine minutes at the second try, then either this test is extremely inconsistent, or the second run was done with a seriously weakened developer. If the negs from the second run are underdeveloped, this will be mostly compensated by the scanner software, so it's not immediately visible except for weak, noisy shadows.

afriman · Apr 21, 2017

As I understood it, there wasn't a first try that took five minutes. Nine minutes was needed with the first try.

pentaxuser · Apr 21, 2017

Rudeofus said:
@pentaxuser: the 22°C number given by elerion referred to the test clip, not to the actual process run.

Thanks I had not realised this. So a clip test is OK at less than 38C, presumably because the strength of the developer can be tested over a range of temps because the strength in the "ability to develop" sense cannot be taken to be the same as "ability to develop correctly" in the sense of obtaining correct colour?

I has assumed that if he was clip testing for developer strength at 22C then it was likely that he would try to develop an exposed film at the same temp. Otherwise why not clip test at 38C which would have been much quicker if he has the ability to do the whole process at 38C?

It will be helpful if the OP can give us the definitive answer on this assumption of mine that his whole process will be carried out at less than 38C.

pentaxuser

trendland · Apr 21, 2017

This may help perhaps first :

C41 alternative temperatures :

CD 45 Celsius = 2 Min.
Bleach 45 Celsius = 2 Min.
Fix 45 Celsius = 2'30" Min.

CD 25 Celsius = 13 Min.
Bleach 25 Celsius = 6 Min
Fix 25 Celsius = 7 Min.

CD 20 Celsius = 21 Min.
Bleich 20 Celsius = 9 Min.
Fix 20 Celsius = 11Min.

Standard :

CD 37,8 Celsius + - 0,3 C = 3' 15" Min
Bleach 35-41 Celsius = 3' - 4' 20" Min.
Fix 33-40 Celsius = 4' 20" - 6' 30" Min.

Color corrections with lower temperature depends / differes to the filmtype in use

with regards

pentaxuser · Apr 21, 2017

trendland said:
This may help perhaps first :

C41 alternative temperatures :

CD 45 Celsius = 2 Min.
Bleach 45 Celsius = 2 Min.
Fix 45 Celsius = 2'30" Min.

CD 25 Celsius = 13 Min.
Bleach 25 Celsius = 6 Min
Fix 25 Celsius = 7 Min.

CD 20 Celsius = 21 Min.
Bleich 20 Celsius = 9 Min.
Fix 20 Celsius = 11Min.

Standard :

CD 37,8 Celsius + - 0,3 C = 3' 15" Min
Bleach 35-41 Celsius = 3' - 4' 20" Min.
Fix 33-40 Celsius = 4' 20" - 6' 30" Min.

Color corrections with lower temperature depends / differes to the filmtype in use

with regards

Thanks, can you say where you obtained these figures from and perhaps more importantly expand on the last sentence. I am not sure what this means in practical terms of what needs to be done with various chemicals and films

pentaxuser

trendland · Apr 22, 2017

pentaxuser said:
Thanks, can you say where you obtained these figures from and perhaps more importantly expand on the last sentence. I am not sure what this means in practical terms of what needs to be done with various chemicals and films

pentaxuser

The times are from Rollei Digibase C41
and it seams to be so that Rollei Digibase
Chemistry is very near familiar to fujihunt c-41 chemicals.
So you use Tetenal C-41 - I thought to Rollei because Rollei get their chemicals
from tetenal too - I guess.

That is not meant as : It is the same chemistry - I am sure it is not of cause.

But these times should be nearly the
same.

Notice : The Time for Bleach and Fix with
20 degree Celsius are astimated.
(I havent use 20 degree Celsius up to now)

But it should work.

The CD time to 20 degrees Celsius is original from rollei Digibase C41.

( 21 Min.)

with regards

trendland · Apr 22, 2017

Comming now to color correction.

You are lower than 37,8 degree CD temperature outside the specification.
This could cause wrong colors.

Escpecially with very low temperatures
you may have the case that your chemistry do work little different to ist
original design.

That will cause some different color problems they are corresponding to different emmulsion familys in different ways.

That is not an absolute must but it is possible.

If this caused - there are smal possabilitys with color correction by developing.

But perhaps you love different colors
Then it will not be nescessary.

with regards

Rudeofus · Apr 22, 2017

pentaxuser said:
Thanks I had not realised this. So a clip test is OK at less than 38C, presumably because the strength of the developer can be tested over a range of temps because the strength in the "ability to develop" sense cannot be taken to be the same as "ability to develop correctly" in the sense of obtaining correct colour?

This would be my interpretation. I am not aware of any developer, which would be active at 38°C but not at 20°C, although obviously development happens much faster at the higher temperature. A quick test done at room temperature is much less hassle than bringing up the CD to 38°C before, then potentially tossing it out.

I would also assume that a CD passing the clip test would develop normally at correct process temperature. The test is not a "is this a C-41 CD?" type test, just a "is this C-41 CD still as active as it was before?". All typical deterioration processes like aerial oxidation, oxidation from use, lowering of pH from dissolved aerial CO2 and bromide/iodide buildup would show up as the same thing: change in activity during clip test.

Mr Bill · Apr 22, 2017

Rudeofus said:
I would also assume that a CD passing the clip test would develop normally at correct process temperature. The test is not a "is this a C-41 CD?" type test, just a "is this C-41 CD still as active as it was before?".

Hi, at first glance this would seem to be roughly correct. But probably better to take this more strictly as evidence that the developer has not gone dead, not to prove that it is perfectly all right. The best argument for this is indirect, just look at all the labs who have spent piles of money on control strips and densitometers. If it were possible to get by with only a "clip test," wouldn't at least some of them discovered that?

It is possible for C-41 to have, for example, a high base "stain" level, combined with weak development, such that a clip test would look good, while actual images would come out badly. So while a clip test is probably a good idea, don't trust important film to "old" developer on the basis of only a clip test.

Rudeofus · Apr 23, 2017

Mr Bill said:
Hi, at first glance this would seem to be roughly correct. But probably better to take this more strictly as evidence that the developer has not gone dead, not to prove that it is perfectly all right. The best argument for this is indirect, just look at all the labs who have spent piles of money on control strips and densitometers. If it were possible to get by with only a "clip test," wouldn't at least some of them discovered that?

It is possible for C-41 to have, for example, a high base "stain" level, combined with weak development, such that a clip test would look good, while actual images would come out badly. So while a clip test is probably a good idea, don't trust important film to "old" developer on the basis of only a clip test.

Despite common claims from folks here on APUG to the opposite, I am firmly convinced, that 99.99% of all C-41 material is printed through hybrid work flow these days, and that color crossover, which scared generations of print lab workers, is a non-issue for most practical purposes today. Severe underdevelopment, on the other side, which this simple "turns test clip dark in x minutes" type test easily catches upfront, is and continues to be a complete show stopper for any work flow.

You can't achieve control strip level perfection with unreplenished kit chems that have been reused a few times and stored for weeks in between. At this point you are so far away from "within control strip limits", that a simple "turns test clip dark in x minutes" type test is fully sufficient.

Gerald C Koch · Apr 23, 2017

It is important with these 'clip' tests that you use working strength developer and not a concentrate. The concentrate can be on its last legs but there is still enough developing agent left to darken the film. However once diluted the developer will not be able to provide a positive test.

Mr Bill · Apr 23, 2017

Rudeofus said:
Severe underdevelopment, on the other side, which this simple "turns test clip dark in x minutes" type test easily catches upfront, is and continues to be a complete show stopper for any work flow.

That's pretty much what I said, in these words, "But probably better to take this more strictly as evidence that the developer has not gone dead, not to prove that it is perfectly all right. "

With regard to a simple clip test in trying to PROVE that a C-41 developer IS GOOD, here's a couple hypothetical cases where the test would mislead you: 1) the developer has been contaminated with bleach - this produces a high stain level (aka base + fog density), resulting in a dark clip test which presumably is seen as ok. But for practical purposes the developer is virtually unusable. 2) Assume a C-41 kit has a combined bleach-fix (aka blix), and that the developer is "going bad," resulting in very weak development which ought to show up on the clip test. But... if the blix is also failing then it will leave lots of silver/silver halide behind, causing the clip test to be dark even though the developer is in poor condition.

To restate my view: a simple clip test is probably good to prove that C-41 developer has not gone dead. But it can't prove that the developer IS FULLY GOOD. This pertains only to C-41 (not to b&w).

elerion · Apr 24, 2017

So far, I'm getting good results. Of course I'm not trying to determine the perfect condition of the CD.
I know how much time it's been stored, when I mixed it, how many rolls I developed, and based on that info, and the last results, I assume it will work fairly well. If I have just a slightly suspicion that CD could have been contamined by any other chem, I discard it right away.
This is the best I can do, so far.
I sometimes do color wet printing (RA4) and I get more or less good colors.
I say "mor eor less", because it's not funny to do a lot of trial-and-error to get the exact color.
I find it much more rewarding and fun to just get nice and sometimes slightly original results.

The reason why I do at 22ºC is just because is quicker than heating the developer up to 38°C.

Quick C41 chemical test

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