Evaluating developer aging -- How to do it?

grainyvision · Nov 30, 2021

I've recently tried to take a stab at measuring how my self-created developers age. This thus far ends up being a set of density charts that look like this (GVL1 being my developer, D-72 being there for control)

These charts are enough to see that my developer has not shown significant degradation with long development times but that overall activity is lower. However, I feel like there's more to aging that I should be measuring but I'm not really sure what to be looking for in this. Like should I be measuring more things to evaluate this? Should I consider adding other papers, is RC "too" consistent?

FYI, for developer info, this is a no-dilution PQ paper developer which has thus far survived almost 2 months and probably 40 8x10 prints.

I'm wondering if it is possible to do the same thing for a film developer as well. Sensitizing film consistently is quite a challenge in my current situation and my current idea (Which kinda works) is printing a step wedge onto the same glossy RC paper and doing development tests at 1, 2, and 3m, using grade 1 for contrast filtration. The idea being that film is lower contrast than paper, and film is rarely developed to completion. So this should be a reasonable measure? However, I have a developer which doesn't produce fog with any film, yet produces fog on paper and other high contrast/quickly developed materials.

Anyone have any experience with this and have any tips toward measuring the life of a developer objectively? I've long struggled with formulating developers which I expect to be long lasting yet ending up with unexpectedly under developed film.

ic-racer · Dec 1, 2021

Measure the time to appearance of the dark parts of the image. That is what I do.

Andrew O'Neill · Dec 1, 2021

I use the emergence/factorial method. I keep track of the time when a mid gray appears, then apply a factor.

grainyvision · Dec 1, 2021

Andrew O'Neill said:
I use the emergence/factorial method. I keep track of the time when a mid gray appears, then apply a factor.

I mean, this can work for print developers pretty well, but not for panchromatic film.

Andrew O'Neill · Dec 1, 2021

grainyvision said:
I mean, this can work for print developers pretty well, but not for panchromatic film.

Yes, but I thought this was mainly about print developers... I guess for film developers, it would only be a concern for replenished systems such as Xtol-R.

gone · Dec 1, 2021

I'm with Andrew, assuming this is just about print developers. If it is, just make a test strip and a test print and that will tell you everything, there is no other quick and practical way (that I am aware of) to know how long a print developer will last, or what it's level of activity will be during a print session. There's so many variables....size of the prints, ambient temp, just a lot of stuff.

But since these are your own home brew developers, yes, a chart like you show here could be very helpful. Me, I would just try things out in the darkroom and keep tons of notes initially. I want to see what things look like w/ own my eyes, and then make decisions based on that.

kevs · Dec 1, 2021

From memory, many modern RC and PE papers are developer-incorporated for fast machine processing, which may skew your tests results if you're using only RC / PE papers. Non-developer-incorporated FB papers might give a more accurate result. I don't which or if any modern FB papers incorporate developer, but they might, so check the data sheets for advice.

Andrew O'Neill · Dec 1, 2021

kevs said:
From memory, most RC and PE papers are developer-incorporated, which might affect your tests results if you're judging deterioration from the development of RC / PE papers. FB papers might give a more accurate result. I don't know if any modern FB papers incorporate developer, but they might, so check the data sheets for advice.

I thought developer incorporated papers were not made anymore...

kevs · Dec 1, 2021

It was mostly done to allow quick machine processing of RC papers, IIRC. Best to check data sheets.
According to this listing https://www.emsdiasum.com/microscopy/products/photographic/paper.aspx Ilford Multigrade IV RC isn't developer-incorporated. Presumably the new MGRC isn't either.

It's probably a non-issue but worthwhile checking if using older paper stocks. The following is useful if anyone wants to go down that particular rabbit-hole: https://cool.culturalheritage.org/byform/mailing-lists/cdl/1993/0536.html.

MattKing · Dec 1, 2021

To the best of my knowledge there are no longer any developer incorporated papers being manufactured - if by "developer incorporated" you mean papers that will develop on their own if they are immersed in the appropriate alkaline activator.
As I recall based on several posts from Ron Mowrey, paper manufacturers have regularly in the past, and probably continue today, added very small quantities of materials that are developer like to emulsions, because that has the effect of fine tuning the contrast behavior and light sensitivity of those emulsions.
Those additives can have an important effect on the longevity of papers. They probably need to be taken into account when designing and evaluating developers.

kevs · Dec 1, 2021

MattKing said:
To the best of my knowledge there are no longer any developer incorporated papers being manufactured - if by "developer incorporated" you mean papers that will develop on their own if they are immersed in the appropriate alkaline activator.
As I recall based on several posts from Ron Mowrey, paper manufacturers have regularly in the past, and probably continue today, added very small quantities of materials that are developer like to emulsions, because that has the effect of fine tuning the contrast behavior and light sensitivity of those emulsions.
Those additives can have an important effect on the longevity of papers. They probably need to be taken into account when designing and evaluating developers.

Thanks Matt, that shows how long I've been out of the darkroom!

As you were!

Andrew O'Neill · Dec 1, 2021

Well, there must be something in the emulsion to aid in fast development times, compared to fibre based papers.

grainyvision · Dec 1, 2021

I rinse all my papers before development to eliminate the incorporated developer aspect from the equation.

I've tried in the past to just judge using my eyes and results, but often have difficulty figuring out if my technical skills for exposure were poor, something is wrong with a camera, or the developer has begun to go off and resulted in under development. I'd like to have some confidence in the shelf life of my developers. I don't use any developer like xtol that dies without warning, almost all of them invariably just slow down with age. So I never get blank film, but under development can be very detrimental with some of my developer designs, especially given that I tend to prefer a higher gamma and contrast aim typically.

ic-racer · Dec 1, 2021

I thought those were paper curves you posted. When testing the developer activity of film, I do a linear regression of the first 10 or 11 points after 0.1 and use that as an indicator of development activity.
For example you can see the line and the solid black dots (the datapoints for the line) in the diagram here.

grainyvision · Dec 1, 2021

ic-racer said:
I thought those were paper curves you posted. When testing the developer activity of film, I do a linear regression of the first 10 or 11 points after 0.1 and use that as an indicator of development activity.

I know film would likely be more informative for film developers, but paper is so much easier and cheaper to handle.

I'm interested in evaluating the aging of both paper and film developers. Paper is relatively simple since it can be developed under a safelight and worst case if the developer goes off is a bad print or maybe one without as good of dmax, but for film the stakes are much higher since it can be original once in a lifetime type images

MattKing · Dec 1, 2021

Andrew O'Neill said:
Well, there must be something in the emulsion to aid in fast development times, compared to fibre based papers.

More likely it is related to the permeability of the two types of substrate - developer doesn't soak into RC paper.
Using Kodak Polymax T developer as an example (because that is what I have been using) Kodak recommends 0:45 - 3:00 developing time for RC papers and 0:45 - 4:00 developing time for FB papers - very similar.

grainyvision · Dec 1, 2021

michael_r said:
If you want to determine things like keeping properties and throughout capacities for your recipes “seriously”, in the end there isn’t really any getting around proper sensitometry over time, as painful as it is. You need a sensitometer (or equivalent), film, paper, and time.

I'm not trying to short cut it too much... but I guess the main question is will using paper for testing instead of film, on film developers, result in a big missing gap of info or unrealistic expectations? I tend to think not as long as the development is not to completion. I actually have a sensitometer, but using it is so extremely cumbersome on 35mm film that I gave up on it. It also is fixed speed and blue light only which can cause weird unrealistic contrast curves on panchromatic film. Currently I have precisely measured enlarger settings and a step wedge that I'm using for sensitizing, but I guess the weak spot there is the enlarging bulb

edit: Also the sensitometer is fixed speed etc. For paper to get a full step wedge I have to expose it 4 times, which is basically impossible to do consistently given the design of the device. I've not seen any good sensitometer for this purpose. One thing I could do of course is buy FP4+ control strips, but I wouldn't have the benefit of contrast curves with that, which may change with age with some developer designs (such as getting same midtone density, but missing shadow detail)

AgX · Dec 1, 2021

grainyvision said:
I've recently tried to take a stab at measuring how my self-created developers age. This thus far ends up being a set of density charts that look like this (GVL1 being my developer, D-72 being there for control)

These charts are enough to see that my developer has not shown significant degradation with long development times but that overall activity is lower. However, I feel like there's more to aging that I should be measuring but I'm not really sure what to be looking for in this. Like should I be measuring more things to evaluate this? Should I consider adding other papers, is RC "too" consistent?

FYI, for developer info, this is a no-dilution PQ paper developer which has thus far survived almost 2 months and probably 40 8x10 prints.

I'm wondering if it is possible to do the same thing for a film developer as well. Sensitizing film consistently is quite a challenge in my current situation and my current idea (Which kinda works) is printing a step wedge onto the same glossy RC paper and doing development tests at 1, 2, and 3m, using grade 1 for contrast filtration. The idea being that film is lower contrast than paper, and film is rarely developed to completion. So this should be a reasonable measure? However, I have a developer which doesn't produce fog with any film, yet produces fog on paper and other high contrast/quickly developed materials.

Anyone have any experience with this and have any tips toward measuring the life of a developer objectively? I've long struggled with formulating developers which I expect to be long lasting yet ending up with unexpectedly under developed film.

I am completely lost with those graphs.

Dmax = 2.7 but Dmin=19 ? What are you talking about?

What does "m" mean? Months , minutes?

What do you mean by "aging"?

grainyvision · Dec 1, 2021

AgX said:
I am completely lost with those graphs.

Dmax = 2.7 but Dmin=19 ? What are you talking about?

What does "m" mean? Months , minutes?

What do you mean by "aging"?

These are just step numbers on the step wedge. The "m" is minutes of development time. This is mainly for my own usage so I haven't bothered to do any unit conversion and more extensive labeling

snusmumriken · Dec 5, 2021

Ashley, I'm not clear whether you really want a numerical answer, or something more practical like an index of developer exhaustion? Since the aim is paper-related, I'm inclined towards the latter, and I wonder whether some adaptation of Barry Thornton's thoughts on contact sheets (here) might be your answer?

I would expect an ageing developer to increase fog level and to lower contrast. I may be talking rubbish here (please tell me if I am), but if you include a Zone 1 and a Zone VIII exposure of some uniform textured surface on each roll of film, you should be able to determine the exposure for (base+fog), Zone 1 density and Zone VIII density from your developed negatives simply by printing test strips as described by Thornton (I think!).

I'd be interested to know whether anyone thinks this idea has legs?

ic-racer · Dec 5, 2021

The question was answered. The slope of the curve is the developer activity.
Sensitometers with glue or green or white light won't affect one's ability to determine changes in the slope.

grainyvision · Dec 5, 2021

snusmumriken said:
Ashley, I'm not clear whether you really want a numerical answer, or something more practical like an index of developer exhaustion? Since the aim is paper-related, I'm inclined towards the latter, and I wonder whether some adaptation of Barry Thornton's thoughts on contact sheets (here) might be your answer?

I would expect an ageing developer to increase fog level and to lower contrast. I may be talking rubbish here (please tell me if I am), but if you include a Zone 1 and a Zone VIII exposure of some uniform textured surface on each roll of film, you should be able to determine the exposure for (base+fog), Zone 1 density and Zone VIII density from your developed negatives simply by printing test strips as described by Thornton (I think!).

I'd be interested to know whether anyone thinks this idea has legs?

I'd like to be able to measure aging for a paper developer, but for film developer it is much more important, especially since with paper devleopment is often to completion which means the journey to get there doesn't matter quite as much.

My biggest issue is just sensitizing film easily and consistently. I've considered using FP4+ control strips even, but it gives much less information, especially around shadow detail which I've observed can be lost in some developer designs when aged. They also do not have sprockets and my normal processing method with reels requires sprockets.

ic-racer said:
The question was answered. The slope of the curve is the developer activity.
Sensitometers with glue or green or white light won't affect one's ability to determine changes in the slope.
View attachment 292503

The one sensitometer I have does not keep the film flat due to its design, and does not give enough exposure for a 100 ISO film at max setting. Working with it in complete darkness is a very painful and annoying endeavor, and then I'm unsure how best to store the test strips also. The test spots are also so extremely small that they are difficult to accurately measure. Sensitometers are also really hard to buy it seems in comparison to densitometers. This is why I'd rather use a light source and step wedge

snusmumriken · Dec 5, 2021

grainyvision said:
I'd like to be able to measure aging for a paper developer, but for film developer it is much more important, especially since with paper devleopment is often to completion which means the journey to get there doesn't matter quite as much.

Ashley, did you read the Thornton article before you wrote this? It isn't talking about paper developer, it's talking about the whole process as a whole. In your case, the variable is the developer. If you keep everything else constant, you have a handle on how the developer is changing.

grainyvision · Dec 5, 2021

snusmumriken said:
Ashley, did you read the Thornton article before you wrote this? It isn't talking about paper developer, it's talking about the whole process as a whole. In your case, the variable is the developer. If you keep everything else constant, you have a handle on how the developer is changing.

this is why curve measuring should be only a minor part of the overall picture in general... BUT. The biggest issue I've found is just a perfectly consistent subject for film photographs. I don't have a space I can dedicate for this purpose, so a step wedge is the next best thing. I'm definitely aware the absolute numbers mean less than the relationship between all of the numbers as a whole. In fact, I've often made step wedges to compare contrast curves by eye without ever measuring anything... and maybe that's accurate enough, but it is subjective and hard to share those results and you also need something conducive to human vision. Ie, you need fairly large spots to compare. It's difficult to judge a step wedge with spots that are 1mm square in size, and this was the struggle I've had with the sensitometer I have and why I stopped trying to use it

Also the human eye can be easily tricked. I've had developers produce prints I thought were excellent until using a control developer like D-72 and the prints beside each other show that the one I thought was good could actually have been a lot better... so while numbers shouldn't be the main focus, it should be involved since the human eye is easily tricked

RalphLambrecht · Dec 5, 2021

grainyvision said:
I've recently tried to take a stab at measuring how my self-created developers age. This thus far ends up being a set of density charts that look like this (GVL1 being my developer, D-72 being there for control)

These charts are enough to see that my developer has not shown significant degradation with long development times but that overall activity is lower. However, I feel like there's more to aging that I should be measuring but I'm not really sure what to be looking for in this. Like should I be measuring more things to evaluate this? Should I consider adding other papers, is RC "too" consistent?

FYI, for developer info, this is a no-dilution PQ paper developer which has thus far survived almost 2 months and probably 40 8x10 prints.

I'm wondering if it is possible to do the same thing for a film developer as well. Sensitizing film consistently is quite a challenge in my current situation and my current idea (Which kinda works) is printing a step wedge onto the same glossy RC paper and doing development tests at 1, 2, and 3m, using grade 1 for contrast filtration. The idea being that film is lower contrast than paper, and film is rarely developed to completion. So this should be a reasonable measure? However, I have a developer which doesn't produce fog with any film, yet produces fog on paper and other high contrast/quickly developed materials.

Anyone have any experience with this and have any tips toward measuring the life of a developer objectively? I've long struggled with formulating developers which I expect to be long lasting yet ending up with unexpectedly under developed film.

for film developer, I use one-shot;always fresh.
for paper developer, I use D72 and can tell by color and smell when it is time for fresh. Your method is far more accurate than mine.

Evaluating developer aging -- How to do it?

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