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Gerald C Koch
01-13-2012, 10:21 PM
Hypersensitization of film was still being done for astrophotography in the 1990's. I do not know whether this practice still continues but I would suspect that it still does.

Ryuji
01-13-2012, 10:59 PM
D-76 suffers an increase in pH due to oxidation. This has been known for a very long time. Various modifications have been proposed to the original formula to provide better buffering such as D-76d which contains 8 g/l each of borax and boric acid. The change in activity led me to abandon the use of D-76 decades ago. I personally would not describe this developer as being reasonably buffered.

You are mixing two different issues here.

Any solution will increase pH if some of the constituents react to generate base in the solution. You are merely stating that D-76d is more heavily buffered than D-76. Buffer is not all or nothing deal. It is a matter of degree, and the question is what degree is sufficient for the application. If you don't keep D-76 stock solution for a long time the original formula is sufficient.

albada
01-14-2012, 11:18 AM
That particular case, everything is reversible reaction and nothing leaves the system so it doesn't matter as long as the end product and pH meet your needs.

Thanks. That's very good to know.
When working with concentrates versus directly mixing into water, the order will change, and it's good to know the end-result will be the same.

Mark Overton

Rudeofus
01-15-2012, 10:56 AM
http://www.apug.org/forums/forum216/69617-shaping-tone-curve-rodinal-negative.html

This will help you shape your tone curve.
Thanks, Thomas, I am fully aware that "stand development" (I put it in quotes because agitation does take place every so often) combined with weak dilutions can reduce contrast in a neg. The important point is, though, that not all developers respond to this in the same way, I would imagine a strongly buffered developer does this much less than a poorly buffered counter part, all other things the same. Rodinal is known to work extremely well with stand development. Its other big plus is that it is very well characterised after so many decades of heavy use. There are, however, hopefully some additional ways of achieving a flatter curve in the highlights which also work with devs more suitable for e.g. Delta 3200 (I have nothing against TMZ except that it doesn't come in 120 format).

PE has written about swelling agents for the gelatine like urea (http://www.apug.org/forums/forum37/38821-superadditivity-developers-beyond.html) which foster development and grain growth. It would be interesting to find the opposite of these swelling agents so less fresh dev reaches the silver halide. In the same thread he wrote that sulfite regenerates HQ, so putting in less or no sulfite into the mix may also help me get closer to my goal (no idea whether it does the same with phenidone/ascorbic acid). Lots and lots of silly ideas which show how little I understand but which indicate to me that there is something which gets me there. Assuming I don't care about grain size and dev durability I can safely play with the sulfite content (I know, I know, pH value ...).

PS: I learned today how spoiled and dumbed down I am from using premade developers. It took me hours to get Na2SO3 and borax to dissolve in water, same problem of course with phenidone in propylene glycol. I also learned the hard way that it is not feasible to specify 0.058g of a substance which is sold in pellets :whistling: Oh well, noob lessons learned :p. I will hopefully have everything mixed until tonight (writing this while the borax dissolves) and can report back later.

PPS: Mark, some of the substances you specified come with varying amounts of H2O bound to the crystal grid. For now I assume you mean Na2BO2 * 4 H2O when you specify "Sodium metaborate". Please tell me if this is indeed the case.

Photo Engineer
01-15-2012, 01:15 PM
Sodium Sulfate is one of the best anti-swell agents for gelatin.

PE

Thomas Bertilsson
01-15-2012, 01:48 PM
Thanks, Thomas, I am fully aware that "stand development" (I put it in quotes because agitation does take place every so often) combined with weak dilutions can reduce contrast in a neg. The important point is, though, that not all developers respond to this in the same way, I would imagine a strongly buffered developer does this much less than a poorly buffered counter part, all other things the same. Rodinal is known to work extremely well with stand development. Its other big plus is that it is very well characterised after so many decades of heavy use. There are, however, hopefully some additional ways of achieving a flatter curve in the highlights which also work with devs more suitable for e.g. Delta 3200 (I have nothing against TMZ except that it doesn't come in 120 format).

That article is not about standing development. It is about using agitation as a tool to shape the tone curve. 1m agitation intervals will cause a different tonality than 5m agitation intervals.
This works well with Rodinal, but Xtol works equally well, as does Edwal 12. (Those are the developers I have used this way, and have experience with using this technique).
Rodinal works very well at the 1+50, or 1+25 dilution too using this technique.

I posted the link, because Ryuji said it was very difficult to alter the tone curve because it was very much a characteristic of the film used. I counteracted that comment by showing that you can override the tonality of some films (TMY-2, Tri-X 400, FP4+, TMX, Acros, Delta 3200, which have long straight curves) and create a shoulder by slowing down agitation. I do it myself every single time I develop film.

Rudeofus
01-15-2012, 03:05 PM
@PE: can you give me any details about quantities to use for the effect I want? Is the number from the dark room cookbook (105g/1l) a good starting point?

@Thomas: I understand the difference between stand developing and what you suggest in your article. Stand development is one extreme which would bend the characteristic curve a lot, frequent agitation is the opposite extreme which creates a straight(er) curve, and your suggestions cover the range in between to fine tune the outcome. I'm also surprised that Ryuji questioned the shapeability of the characteristic curve since I have read too many times that different developers yield different curves.

@Mark: you recipe worked, I developed for 12 minutes (attempted 2 stop push), agitated every 1/2 minute and got reasonable looking negatives. I'll try to print a few of them on Wednesday and will report what I find especially with regard to speed and highlights. Please note that I am aware that exposing film with the builtin meter of my Rollei 35s, pushing it two stops and then looking at the result is not the recommended way of evaluating a developer :whistling: I do have a densitometer at my darkroom so if questions about my negatives arise I can take some measurements (e.g. min and max density).

Photo Engineer
01-15-2012, 03:31 PM
You can use Sulfate at 25 - 100 g/l. The effect depends on concentration and you can salt out your developer and get crystals forming in it if you use too much. Also, the effect may be smaller than you wish.

PE

Alan Johnson
01-15-2012, 04:35 PM
I have done some testing of PC-TEA where the developer is dilute but quite high amounts of sulfite added and I could not get grain as fine as Xtol(or DS-10,Mytol,E-76).It seems to me quite likely that the high phenidone(or derivative), ascorbate and borate in these latter contributes to the fine grain.Therefore the concentrate has to be high in phenidone,ascobate and borate.The chemistry gets to the limits of what is known,esp wrt the formation of glycol borate complexes and their dissociation,when making these concentrates.It's quite a project.

Ryuji
01-15-2012, 04:38 PM
I posted the link, because Ryuji said it was very difficult to alter the tone curve because it was very much a characteristic of the film used. I counteracted that comment by showing that you can override the tonality of some films (TMY-2, Tri-X 400, FP4+, TMX, Acros, Delta 3200, which have long straight curves) and create a shoulder by slowing down agitation. I do it myself every single time I develop film.

Well, the sensitometric data shown at your link does show some visible difference in the curve, but if you compare that to the shoulder of Verichrome Pan or Panatomic-X (which are generally referred to as films with shoulder) or even Delta 3200 or TMZ, you are not even halfway there. I would not state that effect as if you can switch one type into another.

The best way to obtain the "shoulder effect" in film characteristics today is to use paper emulsion with toe, and use print developer that does not trim the toe.

Ryuji
01-15-2012, 04:42 PM
I have done some testing of PC-TEA where the developer is dilute but quite high amounts of sulfite added and I could not get grain as fine as Xtol(or DS-10,Mytol,E-76).It seems to me quite likely that the high phenidone(or derivative), ascorbate and borate in these latter contributes to the fine grain.Therefore the concentrate has to be high in phenidone,ascobate and borate.The chemistry gets to the limits of what is known,esp wrt the formation of glycol borate complexes and their dissociation,when making these concentrates.It's quite a project.

Sorry, nope. The primary factor is the pH and the concentrations of the *effective* or dissociated developing agent molecules. You could use zero borate, 2g/L ascorbate, ..., 35g/L sulfite, etc., and still get good fine grain if the pH is 8.00 or 8.20 range and do not underexpose or overdevelop.

Alan Johnson
01-15-2012, 05:21 PM
So are you saying that at a given pH increasing the phenidone & ascorbate concentrations by a factor of say,10, increases the rate at which the grains develop but has no effect at all on their size?

Thomas Bertilsson
01-15-2012, 05:40 PM
Well, the sensitometric data shown at your link does show some visible difference in the curve, but if you compare that to the shoulder of Verichrome Pan or Panatomic-X (which are generally referred to as films with shoulder) or even Delta 3200 or TMZ, you are not even halfway there. I would not state that effect as if you can switch one type into another.

The best way to obtain the "shoulder effect" in film characteristics today is to use paper emulsion with toe, and use print developer that does not trim the toe.

It works for me, is all I can say. With my developer of choice, replenished Xtol, I use it in my own darkroom every time I process film. There are lots of things that will affect the outcome, and the reason for doing this is to be able to use the same emulsion again and again, and the real reason to do that is to be able to know exactly what to expect every time I shoot, with regard to fitting the negative to the paper.

It's one tool, among many, and my motto has been, for a long time now, that it's less important what materials we use, than HOW we use them. It helps me go into the darkroom and print with very minimal waste, both time wise and materials wise. That excites me.

albada
01-15-2012, 05:53 PM
@Mark: you recipe worked, I developed for 12 minutes (attempted 2 stop push), agitated every 1/2 minute and got reasonable looking negatives. I'll try to print a few of them on Wednesday and will report what I find especially with regard to speed and highlights. Please note that I am aware that exposing film with the builtin meter of my Rollei 35s, pushing it two stops and then looking at the result is not the recommended way of evaluating a developer

Good to hear! Coincidentally, I just developed another test-strip with that same formula. It's drying now. This experiment tried a little pushing, but nothing as drastic as yours. :)

From what I'm seeing, this formula is good for pushing. It's extracting more shadow-detail than XTOL, yet without blowing out the highlights.

Mark Overton

Michael R 1974
01-15-2012, 06:13 PM
Well, the sensitometric data shown at your link does show some visible difference in the curve, but if you compare that to the shoulder of Verichrome Pan or Panatomic-X (which are generally referred to as films with shoulder) or even Delta 3200 or TMZ, you are not even halfway there. I would not state that effect as if you can switch one type into another.

The best way to obtain the "shoulder effect" in film characteristics today is to use paper emulsion with toe, and use print developer that does not trim the toe.

Acutance developers such as FX-2 which use small concentrations of developing agent and minimal sulfite can produce pronounced shouldering.

albada
01-15-2012, 06:15 PM
I have done some testing of PC-TEA where the developer is dilute but quite high amounts of sulfite added and I could not get grain as fine as Xtol(or DS-10,Mytol,E-76).It seems to me quite likely that the high phenidone(or derivative), ascorbate and borate in these latter contributes to the fine grain.Therefore the concentrate has to be high in phenidone,ascobate and borate.The chemistry gets to the limits of what is known,esp wrt the formation of glycol borate complexes and their dissociation,when making these concentrates.It's quite a project.

My experience agrees with Ryuji. As an example, here's a formula that gives grain matching XTOL under my 22x loupe, yet has low concentrations of phenidone and other components. This formula is for a concentrate yielding either 5 liters or 1 liter of working solution:



Working volume ----------> 5L .......... 1L
Propylene glycol .............. 75 .......... 15 ml
Sodium metaborate ......... 11 .......... 2.2 g
Ascorbic acid ................... 22.5 ....... 4.5
Phenidone ....................... 0.25 ....... 0.05 g
Propylene glycol to .......... 100 ........ 20 ml (should need to add only 5/1 ml)

pH = 8.0. Use 20ml per liter (1+49 dilution) into water containing 45 g/L sodium sulfite.
Develop for twice XTOL's times.


I tried this developer for the first time yesterday, and the TMY-2 test-strip looks great. The appeal is that it uses only half the sulfite as XTOL, less other chemicals, and can be concentrated to 1+49 dilution. Of course, one must develop for twice as long, but for me, that 7-minute cost more than compensates for the benefits. This formula is similar to diluting XTOL 1+1, but with less phenidone, more buffering and a lower pH to avoid the reduction in contrast. So I'm going to tweak and test this formula some more.
Anyway, it shows that low concentrations can produce grain as fine as XTOL.

My potassium sulfite and dimezone-s are here, so I need to try those out. Man, there's too much to do! Gotta stay focused...

Mark Overton

Michael R 1974
01-15-2012, 06:16 PM
Well, the sensitometric data shown at your link does show some visible difference in the curve, but if you compare that to the shoulder of Verichrome Pan or Panatomic-X (which are generally referred to as films with shoulder) or even Delta 3200 or TMZ, you are not even halfway there. I would not state that effect as if you can switch one type into another.

The best way to obtain the "shoulder effect" in film characteristics today is to use paper emulsion with toe, and use print developer that does not trim the toe.

Acutance developers such as FX-2 which use low concentrations of developing agent(s) and low sulfite levels can produce pronounced shouldering.

albada
01-15-2012, 06:56 PM
PPS: Mark, some of the substances you specified come with varying amounts of H2O bound to the crystal grid. For now I assume you mean Na2BO2 * 4 H2O when you specify "Sodium metaborate". Please tell me if this is indeed the case.

The sodium metaborate I use is what PhotoFormulary.com sells, and I thought it was anhydrous. I just looked up the MSDS on PhotoFormulary's web-site (http://stores.photoformulary.com/images/store_version1/MSDS_Sodium_Metaborate_4_Mol.pdf), and it's the dihydrate version. Surprise! That MSDS says the molecular weight of NaBO2*2H2O is 101.83, instead of the 65.80 that I've been assuming all this time. Wow. Thanks for bringing this up.

That means I've been mixing some H2O into my concentrates. Not a good idea. Fortunately, I've determined the correct amount of sodium metaborate (dihydrate) experimentally in my developers, so they won't need to change. But I'll think about heating any concentrate to drive out H2O.

Mark Overton

Rudeofus
01-16-2012, 01:57 AM
The sodium metaborate I use is what PhotoFormulary.com sells, and I thought it was anhydrous. I just looked up the MSDS on PhotoFormulary's web-site (http://stores.photoformulary.com/images/store_version1/MSDS_Sodium_Metaborate_4_Mol.pdf), and it's the dihydrate version. Surprise! That MSDS says the molecular weight of NaBO2*2H2O is 101.83, instead of the 65.80 that I've been assuming all this time. Wow. Thanks for bringing this up.

Chemistry can be a bitch sometimes ;) I incorrectly assumed you meant the tetra hydrate NaBO2*4H2O so it looks like your recipe still yields results even if the metaborate content is off by quite a bit. Using the same weight of tetra hydrate instead of dihydrate adds only 3/4 of the metaborate to the mix.

That means I've been mixing some H2O into my concentrates. Not a good idea. Fortunately, I've determined the correct amount of sodium metaborate (dihydrate) experimentally in my developers, so they won't need to change. But I'll think about heating any concentrate to drive out H2O.
From what I have understood the main problem with water in stock solution seems to be that water dissolves oxygen which hurts the developer. If you have only trace amounts of water I can't imagine how this would hurt. The 1.2g metaborate dihydrate of your recipe contain about 0.4g = 0.4ml of water, in 30ml of propylene glycol this is a trace amount in my book.

One question for the experts: If so much Na2SO3 is added to the mix, is it necessary to add some chelating agent like Na2-EDTA (Ryuji, I don't care about long term storage now) or Dequest (if I can get this anywhere here), or is iron only a problem with color film?

One more question: I set up a stock solution of metaborate from borax and lye in water. Is this stock solution reasonably stable or does it decompose somehow? If I let all the water evaporate from this mix: can I expect sodium metaborate crystals? If yes, what amount of water can I expect in these crystals?

Ryuji
01-16-2012, 02:54 AM
One question for the experts: If so much Na2SO3 is added to the mix, is it necessary to add some chelating agent like Na2-EDTA (Ryuji, I don't care about long term storage now) or Dequest (if I can get this anywhere here), or is iron only a problem with color film?

One more question: I set up a stock solution of metaborate from borax and lye in water. Is this stock solution reasonably stable or does it decompose somehow? If I let all the water evaporate from this mix: can I expect sodium metaborate crystals? If yes, what amount of water can I expect in these crystals?

1. why are you talking about chelating agent in relation to sulfite? They are unrelated issue. Generally speaking (not in the context of ascorbate developers) chelating agent is used so that calcium scum does not form. That is why EDTA, DTPA or NTA is usually used in packaged developers. They are not really concerned about iron. (MQ and PQ developers are not very sensitive to iron, manganese and copper impurities, where ascorbate developers are super sensitive.)

2. In ascorbate developers, dealing with trace amount of iron impurities from any possible source (including water source and sulfite stock) is crucial for reliability, not just keeping property. I would not use an ascorbate developer without this measure, even for one-shot use, period. My negatives are result of a lot of work. You should study how "sudden death of XTOL" happened. It can happen in just a matter of an hour or two, and it does not discolor the solution at all.

3. Color process is a different problem. You have a lot of iron compounds in bleach bath. In some reversal processing, they need be thoroughly removed or it will turn into stain (very problematic in print processing). But the problem is different in ascorbate developers.

4. You should really get some decent industrial chemistry references. Borate buffer is not a part of elementary chemistry but it is very common in industrial chemistry, and it is definitely important in understanding b&w film developers (as well as making your own). You should have data on concentration dependency, temperature dependency, etc. at your fingertips. Carbonate, phosphate, triethanolamine, diethanolamine, etc., are also important and useful. Those references will also have a chart on the hydration of the compound with respect to temperature and pressure.