Leader Density: D-76 vs Rodinal and others

Arvee · May 24, 2014

Sal Santamaura said:
As this thread died down, I couldn't resist contacting Dick Dickerson and Silvia Zawadzki, the Kodak engineers who invented XTOL. Although retired, Dick and Silvia still get together regularly, and said they'd discuss my question on implications, if any, of pH and water used to mix stock solutions, at their next meeting. I included a link to the thread, which they reviewed.

After considering my distilled water measurements, their response echoed Gerald's comments; it absorbs CO2 from the atmosphere, causing pH to tumble, and offers miniscule buffering capacity. They indicated bringing the water to neutral would be tedious to do and gain me nothing, adding that the amount of CO2 absorbed by the water is likely no different than what perfectly neutral water would absorb while stirring to mix a developer.

Dick and Silvia went on to discuss the sequestrants, buffers and other addenda found in XTOL (as well as other packaged developers) which enable mixing stock solutions with all but the most foul local water. They noted that there could be a small difference in optimum development time for a given film based on one's particular water supply, but, once dialed in, that time would be consistent. The only photographers they suggest might benefit from mixing XTOL with distilled water are photojournalists who travel the world, encountering varying water supplies in different locations. I replied that, since my local municipal system alternates between water sources of substantially different quality, I'll continue to mix XTOL with distilled, since less than $2 every six months or so seems a small price to pay for consistent contrast index results.

I had mentioned to Dick and Silvia that there have been reports lately of XTOL packages being received in breached envelopes that were open to the atmosphere, which seemed to coincide with a change in supplier from Champion to (reportedly) Tetenal. This is a verbatim quote -- with permission -- of their response's final paragraph:

"Of course all of this is predicated on XTOL still being properly manufactured. No reason to think it isn't, but that is something we can no longer vouch for!"

Thank you, Sal, for taking the discussion to the experts for their valued opinion. I never expected this thread to create such a firestorm of active discussion; I figured it had to be either pH (which has now been ruled out with many thanks to DD and SZ) or absorbed oxygen in the manufacturing process oxidizing the developer or just plain contamination. Foolish me, I thought a simple posting might dredge up someone with similar experience and we would put this issue to bed in an exchange or two.

I have long since dismissed the issue as my alternate water source is perfectly viable and now reliable. It was probably some inane shortcut in the manufacturing process of this particular brand of DW that introduced the problem. I have had zero issues since switching to filtered water.

Who knew it would take over a 100 posts to rule out my two perceived notions of possible problem areas! Anyway, thanks to all who contributed.

Arvee · Jun 30, 2017

Hate to wake up a sleeping thread but I thought it worthwhile to pass along further information. Last month, I absentmindedly mixed some D-76 with a gallon of distilled water I had in my storage cabinet. Not observing the knowledge gained in this thread I processed several rolls before I realized my mistake. Fortunately, I saved the rolls intact and hadn't cut them up and sleeved them so I had dates and leaders from the beginning rolls to the most recent. When I realized what I had done, I checked the density of the leaders with an exposure meter and the sun as a light source. The density of the leader of the first roll (FP4) was EV 9 and the last roll (processed 5 weeks after the mix date) had a leader density of EV 11.6, a full 2 2/3 stops less density than the beginning roll.

Yes, i know in a perfect world distilled water has virtually no buffering capacity (as mentioned by several of you) but Kroger distilled water is not manufactured in a perfect world and is not stored in a non-gas permeable plastic container.

Upon further research, I found steam iron manufacturers no longer recommend using distilled water in their irons as the distilled water absorbs enough CO2 to create strong enough Carbonic Acid to corrode the metal inside the iron. If the distilled water can corrode metal, it would certainly be strong enough to weaken the performance the D-76. In the couple of years since this post originated, I have used either tap water or bottled spring water with no observable loss in leader density when decanted and stored in filled/Saran sealed brown Boston rounds, within Kodak's recommended shelf life limits.

As an aside, the recent influx in cannabis growers, who use distilled water in their gardening, have to add a product called pH Up to restore distilled water to its design pH of 7. Apparently using DW with a pH in the 4-5 range causes their plants to not thrive and turn yellow.

Cheers!

Petraio Prime · Jun 30, 2017

Fred Aspen said:
I typically use D-76 1+1 or Rodinal 1+50 for developing my medium speed film (Tmax 100). I noticed when comparing leaders exposed to daylight, the film developed in diluted D-76 has what appears to be much weaker leader density as compared to Rodinal. The D-76 leader when held to the eye is not nearly opaque and objects in sunlight are easily visible through the leader. The Rodinal leaders are virtually opaque and it is difficult to see objects in sunlight through the leader. This is with a freshly mixed, aged a day, batch of D-76 using distilled water for mixing and dilution. The same distilled water is used for the Rodinal dilution.

I went back into old negatives processed with different batches of D-76 and observed the same differences, so that pretty much rules out a bad batch of D-76. Also, highlight densities on properly exposed older frames are weaker than Rodinal processed film. I am using fresh Kodak bags of D-76 and a several year old bottle of Rodinal. The old Rodinal blows away the D-76.

I am using manufacturer's recommended development times but with the vigorous Kodak recommendation for agitation for the D-76 (5 inversions/30 sec) and a much gentler scheme for the Rodinal (2 gentle inversion/1 min.). The D-76 negs are somewhat flat when compared to the Rodinal negs.

My questions:

Does the variation in leader density when exposed to daylight for minutes during loading, etc., occur because D-76 is a much 'softer working' developer compared to Rodinal? Or, perhaps, does it relate to the ph of the respective developers, i.e., borax vs sodium carbonate? Or am I just plain missing something here?

As an aside, a while back I had to use some HC-110 because I was out of D-76 and using Covington's developing recommendations, I got leader densities comparable to Rodinal developed leaders.

Intuitively, it seems to me that Tmax100 film exposed to daylight and developed in most developers for the manufacturer's recommended time would reach near opaque densities in the leader material. Somehow the D-76 doesn't compare.

A quick addition: I checked some leader material developed in Tmax developer a while back and had strong leader density with it as well.

Is there something peculiar about D-76 that doesn't develop leader material to maximum density? I am completely baffled here! I have used D-76 for many years along with Rodinal and simply compensated for the differences when printing. I can put out a decent print from either but the leader density issue finally has me wondering if D-76 negs are not fully developed and should be doing a better job.

From charts I have, it appears that both developers are reaching approximately the same development of CI 0.56 (Rodinal is spec'd in gamma but I concluded that gamma 0.65 is comparable to CI 0.56).

Any thoughts? Are you all seeing similar (weaker) leader densities in your D-76 processing?

Bottom line: I don't believe I am getting full development with my D-76 developed negatives.

You are obviously not processing your film to the same degree of development in these two developers. It's that simple.

Arvee · Jun 30, 2017

Petraio Prime said:
You are obviously not processing your film to the same degree of development in these two developers. It's that simple.

And you have obviously not read the contents of the entire thread!! It's that simple!

Petraio Prime · Jun 30, 2017

Fred Aspen said:
And you have obviously not read the contents of the entire thread!! It's that simple!

Yes, I did. You are getting different degrees of development, either due to the times not being accurate or some problem with the water.

Arvee · Jun 30, 2017

Petraio Prime said:
... or some problem with the water.

Aah, you've got it!

Gerald C Koch · Jun 30, 2017

As a trained chemist I can say that ONCE AND FOR ALL IT IS NOT THE WATER. Anyone that maintains otherwise does not understand the concepts of pH and buffer capacity. As to the argument that it is carbon dioxide dissolved in the water causing the difference let me say the solubility of carbon dioxide is not large and the resulting carbonic acid is a very weak acid incapable of causing what is observed.

Carbonic acid is such a weak acid that its acid salt sodium hydrogen carbonate (sodium bicarbonate or baking soda) produces an alkaline pH when dissolved in water.

Gerald C Koch · Jun 30, 2017

Petraio Prime said:
Yes, I did. You are getting different degrees of development, either due to the times not being accurate or some problem with the water.

Or a problem with the developer temperature.

However as I said before that apparent density of the film leaders is dependent on the particle size of the silver. A fine grain developer like D-76 produces finer grain which appears more transparent.

Arvee · Jul 2, 2017

Gerald C Koch said:
As a trained chemist I can say that ONCE AND FOR ALL IT IS NOT THE WATER. Anyone that maintains otherwise does not understand the concepts of pH and buffer capacity. As to the argument that it is carbon dioxide dissolved in the water causing the difference let me say the solubility of carbon dioxide is not large and the resulting carbonic acid is a very weak acid incapable of causing what is observed.

Carbonic acid is such a weak acid that its acid salt sodium hydrogen carbonate (sodium bi

Thank you.

carbonate or baking soda) produces an alkaline pH when dissolved in water.

Jerry,
First off, I’m not going to engage in any arguments! That said, I have been using D-76 with either tap or spring water over the past three years and have developed many dozens of rolls of FP4 with leader densities equal to those of Rodinal and BT’s Two Bath with zero failures.

Then, using the same equipment (timer, thermometer (Kodak Process 3) and the same protocol), I used D-76 mistakenly mixed with a jug of Kroger distilled water. The first roll was fine; the last roll was a disaster. Again, the only variable in the equation was the water. My new batch of 76, mixed with spring water is just fine. Additionally, the 76 mixed with DW collapsed completely and was completely clear...not brown, a typical indication of oxidation.

I’m not arguing with you on the subject; I still believe the water is the culprit. I know, in theory, DW has no real buffering capacity. I absolutely agree to that, in principle. But, are you prepared to go out on a limb and say Kroger’s product is pristine, pure and has no real buffering capacity similar to lab grade DW?

So, if you still maintain that the water is not the issue, please, oh please, put all your expertise to work and tell me what I am doing wrong!!!

Again, no raised hackles here, I started this thread three years ago hoping to find the solution to the problem. In the end, after switching to an alternate source of water, I haven’t had one single failure in three years but simply mixing a batch of 76 with Kroger DW faithfully recreated the same sequence of failures, right down to the letter!

I am not a chemist; I am a retired EE so please put on your chemist's thinking cap and help me pinpoint the problem if it is not the water!

PS. I am/was a formally trained Shainin Journeyman and spent a huge part of my career traveling the world finding the ‘Red X’ and solving problems for large corporations far more complex than the simple situation described above. Google Dorian Shainin if you’re not familiar with the concept/training. So, if my training has failed me, please point out where I made a wrong turn in my problem solving! If not the water, pray tell, what is it?

Thank you.

ericdan · Jul 2, 2017

Have you made sure that you're using enough developer when using D76 at 1+1?
The tech sheet for D76 also says:

If you use D-76 Developer diluted 1:1, dilute it just before you use it, and discard it after processing the batch of film. Before using the diluted developer, make certain that there are no air bubbles in the solution. If air is coming out of the solution and forming bubbles, let the solution stand until the bubbles dissipate. Don’t reuse or replenish the diluted solution. You can develop one 135-36 roll (80 square inches) in 473 mL (16 ounces) or two rolls together in 946 mL (one quart) of diluted developer. If you process one 135-36 roll in a 237 mL (8-ounce) tank or two 135-36 rolls in a 473 mL (16-ounce) tank, increase the development time by 10 percent (see the following tables).

Thomas Bertilsson · Jul 4, 2017

I'm so glad you solved your problems, Fred!!! Happy shooting!

Leader Density: D-76 vs Rodinal and others

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