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albada
03-12-2012, 05:03 PM
It is usually considered that it is the ascorbate which is used up, as reported by Gainer:
http://unblinkingeye.com/Articles/Synergism/synergism.html

At the end of that article, Gainer recommends an ascorbicacid/phenidone ratio of at least 80:1, and says that an excess above that "serves as a preservative and as a reserve." The ratio in my formula is 148, so it should have considerable reserve of ascorbic acid.

D316 also has .05 g/L of Phenidone, but less ascorbic acid. Have you developed a 36-shot roll in D316? If so, do you recall how many ml of dev you mixed?

Mark Overton

Alan Johnson
03-12-2012, 05:37 PM
Mark,

I have not done the test that you report where density is compared for a short test strip and for a 36 exposure roll.
But I have developed 36 exposure rolls using 10ml of D316 in 500ml sulfite solution.
The required time was about 2.5 times the Xtol 1+0 time.This is not a reliable figure as I used my classic cameras,but it might do for a start.

Photo Engineer
03-12-2012, 06:43 PM
Mark;

That is not a classic upswept curve. It s a normal curve, but underexposed or underdeveloped by about one or two stops. My guess would be underexposure at this time. So, we are just looking at toe, no mid range or shoulder.

The ratio you use is too high and with a full roll of film, the PD is being exhausted.

That is my guesstimate at this time.

PE

albada
03-12-2012, 07:15 PM
That is not a classic upswept curve. It s a normal curve, but underexposed or underdeveloped by about one or two stops. My guess would be underexposure at this time. So, we are just looking at toe, no mid range or shoulder.

Ron, the left end of the toe in that chart has positive slope (not flat), which tells me that I overexposed a little. Kodak's curves start flat. That leaves the option of underdevelopment, and given that the leader's density was only 2.7, I believe it. BTW, what density should a typical leader be?


The ratio you use is too high and with a full roll of film, the PD is being exhausted.
That is my guesstimate at this time.

Would reducing the amount of ascorbic acid (thus reducing the AA/phen ratio) help this exhaustion problem? Or is the only cure to add more phenidone?

Your knowledge is appreciated as always!

Mark Overton

Photo Engineer
03-12-2012, 07:32 PM
Mark;

The maximum density of any film is based on design. Most films try to achieve a Dmax of 3.0 or thereabouts and a Dmin of 0.1 or thereabouts. Overexposure of a piece of leader can actually reduce the maximum achievable density in some films due to "solarization" from the extreme overexposure they sometimes get.

I revise what I said. The film is probably both underexposed and underdeveloped. Try to get a contrast in the mid tones of about 0.6 - 0.8.

Use of less AA will make the problem worse, not better. The solution is to increase PD.

PE

Ian Grant
03-13-2012, 03:20 AM
Does developing a roll of film destroy a certain number of milligrams of developer? I'm still investigating why test-strips are denser than a roll. That happens with both the Dimezone S formula above, and the Phenidone formula below:

Yes developer is used up and exhausted by processing a single film particularly when the level of dev agents is low and dilute.

At the level of Phenidone you have in the second dev 0.05g/l your at equivalent of a PQ version of D76/ID-11 diluted 1+3 and if there's insufficient volume you will be exhausting the developer with a whole film and would get reduced Dmax and contrast. A test strip in fresh dev would suffer no exhaustion and would need a shorter dev time as well.

There's an Ilford reserach article published in the 1950's which discusses the exhaustion rates I'll dig out the details,

Ian

Ian Grant
03-13-2012, 04:55 AM
Mark a rough guide is as follows based on 1955 data:

1g Ag (12 120 films) uses 1.6g Metol or 0.16g Phenidone. - so the exhaustion rate is roughly 0.016g Phenidone per fully developed film.



Sodium sulfite
48 g


Ascorbic acid
7.4 g


Sodium metaborate
4.2 g


Phenidone
0.05 g




So a Tank with 300ml or 500ml of this dev only contains 0.013g (300ml) or 0.025g (500ml) of Phenidone - this is why you're having problems. This also shows clearly why a test strip is OK but a full film has exhausted the developer before full development takes place.

Here are more details of developer exhaustion (http://www.apug.org/forums/forum37/79911-developer-volume-anchells-view-3.html) I gave in a post 18 months ago.

Ian

RalphLambrecht
03-13-2012, 05:12 AM
i'm very interested in seeing this research article.

Alan Johnson
03-13-2012, 12:31 PM
Mark a rough guide is as follows based on 1955 data:

1g Ag (12 120 films) uses 1.6g Metol or 0.16g Phenidone. - so the exhaustion rate is roughly 0.016g Phenidone per fully developed film.


Your 1955 data suggests that the phenidone is not regenerated?

albada
03-13-2012, 12:50 PM
Ian, this is very helpful! Thanks for posting it. I had no idea at what rate Phenidone was consumed/destroyed.

A 24-shot roll in a Paterson tank (325 ml) will have twice as much developer available per frame compared to a 36-shot roll in a stainless tank (220 ml). We want both to develop to similar densities, so this is an important issue.

One question: Pat Gainer's PC-TEA uses only .05 g/L of Phenidone, which is the same as my formula. So I'm wondering: Do folks have trouble with exhaustion with PC-TEA?

Mark Overton

Ian Grant
03-13-2012, 01:37 PM
Your 1955 data suggests that the phenidone is not regenerated?

The second developing agent is also being used up albeit sloweralong with the Borax or Metaborate so all have an efftein diminishing effective development.

There's no suggestion that Phenidone isn't being regenerated in a PQ developer but then Metol is also regenerated in an MQ developer. It's a separate article that discusses measuring Phenidone levels in working (replenishable) developers but it's being used up and needs replacing.


One question: Pat Gainer's PC-TEA uses only .05 g/L of Phenidone, which is the same as my formula. So I'm wondering: Do folks have trouble with exhaustion with PC-TEA?

Mark Overton

Mark, using low levels of developing agents is a fine balance, Gainer's PC TEA doesn't contain Sulphite, if you drop the sulphite level in a developer you get increased activity.

Ian

albada
03-14-2012, 02:19 PM
Is there a chemical which will slow down development?
Restrainers appear to disproportionately affect shadow areas, but what I'd like is a way to slow down overall development, similar to lowering temperature or pH.
The reason for the question is: I will need to boost the amount of developer to prevent exhaustion seen in the last few postings. But that will also boost the development-rate, which I don't want for a couple of reasons. I've read that sugar will slow things down, but I'd probably need too much for it to work in a concentrate. Hmm, maybe I could use honey instead of propylene glycol as the carrier. :)

Mark Overton

Ian Grant
03-14-2012, 03:15 PM
Well Ilford used Glucose (Dextrose) - 20g/litre - in ID-44 which was a p-aminophenol hydrochloride/Metol based developer.

This is a class of developers that haven't really been looked at in recent years but interestingly Crabtree at Kodak Research (US) published a p-Aminophenol hydrochloride/Metol based developer in 1918 for Cine film development. GEK Mees had worked for a time on p-Aminophenol based developers at Wratten & Wainwright (UK) prior to his appointment as Head of Research at Eastman Kodak (US).

Kodak sold p-Amininophenol hydrochloride as Kodelon after WWI and into the 1920's at some stage they switched to selling p-Aminophenol Oxalate as Kodelon before switching back again later.

Ian

Gerald C Koch
03-14-2012, 04:28 PM
Kodak also used sucrose (table suger) 100 g/l to restrain development in bath A of their two bath developer SD-5.

Photo Engineer
03-15-2012, 03:20 PM
Mark;

Your question about having a certain amount of developing agent react with a certain amount of Silver Halide has caused generated some interest from others, and so I thought I might expand on this.

The answer is both yes and no. Hmmm, well it is true. You can write a balanced Redox equation in terms of standard Chemistry, but this does not take place due to the complexity of real life. Remember what I said about chemicals not knowing chemistry. They know what is real, and we write down what we expect. These often differ.

Lets take HQ for example. HQ + AgX > Q + Ag + HX (this is unbalanced, and I know it is - I am simplifying though) So, we write a simple equation, but HQ must be in the form 2H+ and Q= (Ionized HQ) before it really reacts and so the reaction is dependent on the ionization of HQ and therefore on pH. This alters the playing field. And, in the presence of sulfite, Q + SO3= gives HQMS (hydroquinone monosulfonate) which is a developing agent itself and thus there is a secondary reaction to consider. The rate again depends on the amount of Sulfite present and the pH.

Now, lets take a situation where we add some BTAZ antifoggant! This can completely stop the reaction of HQ with Silver Halide depending on level. It throws all equations out the window.

Then on top of this add Metol or PD and the reaction is now governed by superadditivity effects which itself is also governed by pH and in the case of PD by alkaline ring opening of the PD ring.

So, at EK, I never saw an attempt to give a value for this ratio outside of theoretical calculations with the added caveat that warned the reader about the above influences. To do a good job at this, you can only do one sure thing, and that is to establish the minimum amount of developing agent needed on a chemical basis using a balanced equation, and then you must recognize that you are going to need a lot more than that. You also need to consider the agent(s) used, the pH and other ingredients such as restrainers and Sulfite and you should also be aware of side reactions and superadditivity.

Just some thoughts to share with everyone. I am sure that my comments fall short of explaining the full complexity.

PE

albada
03-17-2012, 09:42 PM
Your question about having a certain amount of developing agent react with a certain amount of Silver Halide has caused generated some interest from others, and so I thought I might expand on this.

Thanks for posting this. I suppose it comes down yet again to T&E -- Trial and Error. Mostly error in my case.

However, even with fresh ascorbic acid, I'm getting orange developer and thin neg's when using Phenidone. Dimezone S neg's are thin, but the dev is clear. I don't know what is going on. I boosted quantities to be comparable to XTOL, which meant having three times as much Phenidone in there, and still get orange! So, it's time to order new chemicals just to be certain that nothing went bad. The odd thing is, test strips always have correct density.

BTW, my rolls are dev'd with 220 ml in a SS tank. I've read that XTOL requires at least 100 ml of working solution, so with twice that and my boosted concentration, I figured things would be fine. Not so!

Mark Overton

albada
03-17-2012, 11:30 PM
I must add that underdevelopment of TMY2 (Tmax-400) with a low-pH PC-type developer yields extremely fine grain. My scanner is good at pulling out shadow-detail, so I think from now on, I'll underdevelop film that I plan to scan. Here's an example:

47984

Notice that detail in the woman's black blouse is still visible. In the darkroom, this underdevelopment approach would require using a high contrast VC filter-pack. But I like that fine grain!

Mark Overton

RalphLambrecht
03-18-2012, 02:36 AM
shadow and highlight detail seem to be perfect.

Photo Engineer
03-18-2012, 10:05 AM
Very nice results Mark. Keep going.

PE

RalphLambrecht
03-23-2012, 05:33 AM
[QUOTE=albada;1318148]I mu low-pH PC-type developer yields extremely fine grain. Here's an example:
mark
plese tell us more about this developer.