D-76/ID11 pH change?

TD-16 is the Photographer's Formulary version of D-76H and I use it with TD-16R replenisher.

SS, I had forgotten about PF's TD-16 and wasn't aware that it is available as a replenished developer. Thanks for the tip.

BTW, is the replenisher the same formula as the developer replenished a few ounces after each roll?
-Fred

I do not know the formula for TD-16R. Since D76R has a lot more Borax and a bit more Metol than D-76, I suspect TD-16R (or D-76HR) would do the same with perhaps more Borax and no Hydroquinone. As I remember from the days when I mixed my own split D76, too much Borax can be hard to get into suspension and can crystalize, but so far I have had no problems with TD-16R.

Steve Sloan

Did some more reading and found that Roger Hicks makes reference to the pH problem but specifically tags 'neat' D-76 as the problem. Others in this thread also intimated the problem exists with replenished D-76.

Looking for a specific answer here, does the problem only exist with stock solution and not with diluted D-76?

Or perhaps the problem is marginalized when D-76 is used in the popular dilutions?

Please answer if you know the truth in fact, no speculation please, I am trying to reach a proper conclusion.

Thanks!

-Fred

Fred;

I just went back to both Haist and Mees and James. Haist does not describe this directly in his book anywhere I can find, but Mees and James describe the pH effect of HQ on a developer due to reaction with sulfite. They give no details.

I do know from personal experience that both Dektol and D-76 increase in activity slightly right after mixing. I usually let them sit over night before use. I have heard nowhere of any developer specifically designed to alleviate this problem.

However, Grant Haist devotes a great amount of space in his book to describing the effect of increasing the buffer capacity of any given developer and shows how activity goes up with buffer capacity. He then goes on to show activity as a function of akali type. The implication, not stated, is that with enough alkali you can buffer out this type of problem at moderate pH values say between 9 and 10.5.

Hope this helps.

PE

Thanks, PE, for the information.

-Fred

For anyone who cares, PF claims in their TD-16 datasheet that the effect of the standard D-76 pH rise in terms of contrast index is equivalent to two paper grades. This is based on an aging period of 50 days. Seems John Sexton is correct in pitching any unused D-76 after 30 days.

I've been thinking a lot about this in the last hour or so. At the time Grant was writing that material on pH of developers, his boss was working on HC110 and a few other developers, and my boss and I were working on the same type of problem with color developers. He may have been constrained in what he could publish due to ongoing work, but I do know that he and I discussed this topic.

It seems that a pH value of 10.0 or lower is most stable for borate or carbonate, with carbonate being better. The more alkali you have the more stable it is as well.

This is what goes on. HQ oxidizes to Qinone which reacts with sulfite to form HQ-monosulfonate and sodium hydroxide. The HQMS is lower in activity and the hydroxide raises pH and increases activity. It therefore depends on the amount of rise in pH and the HQMS lower activity which way the developer swings. At the same time, carbon dioxide in the air is reducing the amount of buffer and the pH slowly. I generally see an uptic in activity followed by a drop and leveling off under my mixing and storage conditions.

So, short term you see an increase, then a leveling off and then a slow decline in an unreplenished system. The shape and size of this curve depends on how full the bottle is in which it is kept, how often it is opened and a host of other things, but the initial reaction is inevitable due to the oxygen dissolved in all water. The only way to stop it would be to boil the water and then purge it with nitrogen during mixing. But, this initial reaction will take place between HQ and sulfite and then virtually stop once the oxygen in the water and the head of air / oxygen is used up. So there is an equillibrium that is reached.

So, the stability of B&W developers is based on a lot of factors and the results can go in a variety of directions depending on handling, storing, mixing, use and etc.... That is why Kodak and others suggest a shelf life for mixed developer in a closed container. It also explains in part, why there is a difference between a developer and a developer replenisher, as the replenisher must compensate for the normally observable changes in the developer due to air and also usage.

That is where my thoughts are right now. I'll keep on thinking and reading.

PE

Ok, here is the result of more R&D on my part.

There are two effects with any HQ developer. The first is short term and is described above. It can lead either to an increase in activity or actually a decrease in activity (I've never seen that though), depending on how you mix it. Then the developer levels off and is constant for about 1 month. Then as the HQ falls through a critical level, or the oxidation takes over, then the pH begins to climb again and this takes over as HQ level falls. But, as pH goes up, HQ that remains becomes much more active and so activity goes up again. Finally, the activity falls off after a certain point and the developer becomes inactive.

So, there you have the entire scheme of activity of ALL HQ developers. The extent to which it takes place is as described in the previous post and depends on mixing, storage, amount of HQ, buffer, sulfite and any co-developers. This is a very complex and hard to understand process and varies in almost every instance! The reformulation of D76 took place in about 1930 to correct, as much as possible, for this problem.

PE

PE,

Thanks once more for the detailed analysis. Your description fits most of the anecdotal information I have read on the web including this comment from Sexton:

NOTE: If you use D-76 developer be sure to use FRESH D-76 (not some that has been sitting around in a half-full bottle for a month!) As D-76 ages a chemical compound, hydroquinone monosulfonate, is formed. This chemical compound will INCREASE the activity of the developer and the contrast of your negatives in a big way with T-MAX. When mixing a gallon of D-76 I suggest storing it in 4 one-quart glass bottles filled to the brim. In this way you can work out of one bottle while the others remain full to minimize oxidation. If in doubt about the age of chemical ... dispose of it. There appears to be no similar aging problem with the T-Max system of developers.

I would definitely suggest that this is not exclusive to T-Max film but would think that T-grained products are much more susceptible than conventionally grained films.

I have gone to T-Max RS developer in a replenished system to avoid this problem for the time being.

Your contribution is much appreciated!

-Fred

Sexton's comments are quite relevant for other developers like X-tol. I always mix the 5 litre pack and split it into one 2.5 litre bottle as my working solution, and smaller bottles for replenishment. It's actually common senses.

Ian

Ian,

I have been using the Vacu-Vin pump and 750ml brown wine bottles for several years with great success. I believe it is the best system out there to combat oxidation.

Also enjoyed the process of collecting the brown wine bottles!

-Fred

Actually Sexton's comment is technically incorrect. HQMS is lower in activity, but it produces a byproduct of Sodium Hydroxide as it is formed. This causes the rise in pH.

One way to check D-76 is to measure the pH 1 day after mixing. Then when you go to use it, remeasure the pH. If it is higher or lower by more than say 0.2 units, do not use it!

PE

Thanks for the limit parameters. I will use that information.

-Fred