Progress on XTOL-concentrate

Gerald C Koch · Aug 2, 2012

I only mentioned mannitol because it is what is typically used when titrating boric acid. Boric acid combines with glycerol which is also used for the purpose mentioned. The only restriction that I know of is that the OH groups must be on adjacent carbon atoms. Of course this is always true with glycols.

The carbon backbone can be either aliphatic or aromatic an example of the latter is catechol. In the case of catchol the developing capability is effectively destroyed by the formation of the borate ester. The only change in a borate buffer system would be the pH with the addition of the glycol.

albada · Aug 3, 2012

Those of you who run test-strips of neg's might be interested in my latest test-setup:

The strip is held down with hobby-magnets, with corresponding magnets under the bottom. The big white thing is my latest addition: It's a baffle to prevent developer from rotating in the tank and developing the outside more than the centre. It's a PVC extrusion which happened to fit well, but anything that blocks rotation of fluid should work. I glued shims on the bottom so it won't touch the neg. The neg you see is in fixer, and was developed in XTOL. Here's the graph of that neg:

My goal is to get corporate-quality test-results on a home-budget. If somebody has a better idea for developing strips uniformly, I'm all ears.

Mark Overton

albada · Aug 3, 2012

Michael R 1974 said:
Mark - you've probably answered this before, but how are you exposing the test strips?

I place a 4x5 Stouffer transmission wedge on a uniformly lit portion of my light-table. After waiting at least 5 minutes for the florescent bulbs to completely warm up, I shoot it with an OM-1 set to 1/60 using a 50mm macro lens at f/3.5 (wide open). I chose 1/60 because (1) my shutterspeed tester says the OM-1 is very consistent at that speed, and (2) it covers exactly one complete cycle of any 60 Hz flicker in the bulbs, so that any such flicker will not affect exposure. To insure consistency, I shoot an entire roll at once, and cut out the strips as needed.

This system works fine, but I think using a reflection step tablet outdoors in sunshine would be better because you could stop down the lens and get maximum sharpness. With my setup, I need to perform sharpness-tests separately.

Mark Overton

albada · Aug 5, 2012

Discouraging results:
I can't get a concentrate containing Dimezone-S to stay in solution. Either immediately or in a few days, cloudiness begins appearing, and the concentrate eventually separates. Concentrates using Phenidone have not had this problem. In fact, after mixing a Dimezone-based concentrate which immediately clouded, I mixed the same formula using Phenidone with no problems (so far). I believe this clouding is the crystallization that PE described a couple of weeks ago (there was a url link here which no longer exists) and (there was a url link here which no longer exists). There is something about Dimezone-S that encourages crystallization of a PG-based concentrate. Even substituting some metaborate with TEA didn't help.

Dimezone-S is preferable to Phenidone because my tests show that, at normal pH-levels, it has lower fog and slightly finer grain. To get Phenidone to match Dimezone-S's grain and fog-level, pH must be dropped to 8.0 or lower. The developer D-316 that Alan Johnson is testing uses this low-pH approach.

Also, I doubt my cream-and-squeeze-tube idea will work because the separation is ongoing, gauging by watching the bottle over a couple of weeks. So we'd need to stir the cream and PG before using, like natural peanut-butter. That means we cannot allow this crystallization to occur. Any ideas how?

If all else fails, it's back to Phenidone and a pH of 7.9 or 8.0.

Mark Overton

Gerald C Koch · Aug 5, 2012

Dimezone was developed to avoid the problem of hydrolysis that occurs with Phenidone in alkaline solution. Unfortunately Dimezone turned out to be less soluble in water than Phenidone. To correct this the structure of Dimezone was altered slightly to make Dimezone-S (S for more soluble). Google the three structures to see what was done. At the pH of the developer you are working on there would be no problem with hydrolysis. So there is no reason that you cannot use Phenidone. I have never heard anyone other than yourself say that Phenidone produces more fog than Dimezone-S. A small amount of fog is always produced during development and really cannot be avoided. If you attempt to eliminate all fog produced by a developer with bromode or benzotriazole the activity of the developer is serverely compromised.

As far as activity there does seem to be less activity with the two Dimezones as compared to Phenidone that cannot be explained by the slight increase in molecular weights. So replacing one developing agent for the other is problematic in this respect. Perhaps this accounts for the increase in fog that you observed when Phenidone was used. You were simply using more Phenidone in relation to Dimezone-S.

Yeats ago there was a developer called Huebl paste which was produced by grinding Glycin, sodum sulfiie, and potassium carbonate together in a mortar. A portion of this paste was then dissolved in water to make a developing solution. (Huebl is an alternative spelling of the man's name when there is no umlaut U in the type set)

Alan Johnson · Aug 5, 2012

Some Mytol (contains phenidone) I kept in a sealed glass bottle lasted over 3 years,by 5 years it failed due to phenidone hydrolysis I believe.Unless you are planning to present your concentrate to a Museum I daresay phenidone would be adequate for the purpose, particularly as the unmixed concentrate has a lower pH than the working solution.

albada · Aug 6, 2012

@Jerry: The symptoms of crystallization are the developer turning white like milk, and then separating over days. This happened to me once when there was no developer present. But the concentration was extremely high because I was trying to find a solubility-limit for PG. So I learned that PG + sodium metaborate + ascorbic acid can crystallize. The Dimezone S seems to encourage and/or cause it though. So I think something other than hydrolysis is happening.
Also, Phenidone's higher fog is based only on my observations. But when I drop pH, fog-levels are comparable. One interesting thing I've noticed: Phenidone is almost exactly twice as active as Dimezone S in these formulations I've been testing. Odd, isn't it? Formulas I've seen more commonly use a factor of something like 1.33. But my densitometer tells me it's 2.0. Go figure...

@Alan: Regarding the 3-5 year lifetime of Mytol: Was your Mytol the original created by Paul Lewis, or the organic concentrate created by Jordan Wosnick which he calls "Instant Mytol"? I have a bottle of the concentrate mixed 9 months ago, and it shows no sign of crystallization.

Anyway, this crystallization-issue with Dimezone-S got me thinking about a developer I devised 6 months ago using Phenidone. So I re-mixed and ran another test-strip with it. Here's the one-litre formula for mixing directly into water:

45 g Sodium sulfite
2 g Sodium metaborate
4.5 g Ascorbic acid
2.45 g Propylene glycol (yes, grams)
0.05 g Phenidone (which was premixed into the above PG as a 2% solution)

pH = 8.05 to 8.1. For TMY2: 13.25 minutes at 20C.

And the density-curves comparing it with XTOL:

I've never seen such close graphs. The grain looks the same as XTOL under close exam on the light-table with 22X loupes.
Keeping sulfite separate, this formula should be able to be dissolved into PG, with a total volume of 20 ml, yielding a concentration ratio of 6.55/20 = 0.33, and a dilution of 1+49.
Alan: This is the same as D-316, but with the metaborate changed from 2.2 g to 2.0 g. So it's almost the same developer.
But it's rather different from XTOL. The dev-times are different, and more importantly, films respond to pH differently, so dev-times won't change by a simple factor. So this would require more testing than an XTOL-clone.

I think I'll try an XTOL-clone with Dimezone-S again, but using TEA instead of sodium metaborate. If the crystallization is from by-products of the reaction of metaborate with ascorbic acid, then TEA might fix the problem.

Mark Overton

Rudeofus · Aug 6, 2012

albada said:
So I learned that PG + sodium metaborate + ascorbic acid can crystallize. The Dimezone S seems to encourage and/or cause it though. So I think something other than hydrolysis is happening.

This is just a simple theory based on lack of knowledge, but could it be that the precipitate is oxidized ascorbate?

Here is what hints in that direction:

Oxidized products of ascorbate have no distinct color, i.e. you don't see when it happens in water.
We know that Phenidone/Dimezone S catalyzes oxidation of ascorbate, that's why it is superadditive
We know that this happens more likely in caustic environment, hence you see it faster with metaborate

A very quick'n'dirty test would be, of course, if you would try developing a test clip of film with the soup once it precipitates.

albada said:
And the density-curves comparing it with XTOL:
I've never seen such close graphs. The grain looks the same as XTOL under close exam on the light-table with 22X loupes.

I would like to know to which extent variations in composition have a visible effect on characteristic courve, grain, sharpness, etc. Since you have obviously done lots of experiments before you came up with your final result, could you comment on that? Would a 10% variation make a big difference or does it take much more before you saw anything different?

Alan Johnson · Aug 6, 2012

Mark,

My Mytol was the water based solution from p89 of the Film Developing Cookbook.The 3 year life in absence of air has not been verified by others AFAIK.For Dimezone-S, 7.5 year some life was reported with anaerobic Xtol:
(there was a url link here which no longer exists)
Your precipitate may be glycol-borate complex ,we will never know.I don't think esters are formed at the mixing temperatures you use:
http://www.chemicalforums.com/index.php?topic=41216.0

For other PC developer PC-TEA when selecting development times for different films I have used a simple multiplier of Xtol time,is there any reason not to use this with one of the concentrates?

Gerald C Koch · Aug 6, 2012

Rudeofus said:
We know that Phenidone/Dimezone S catalyzes oxidation of ascorbate,

This is just not true you misunderstand the meaning of catalysis. Ascorbate ion reduces oxidized Phenidone/Dimezone back to the parent compound. However this is a moleculae for molecule process not the massive oxidation of the ascorbate that your statement implies.

Rudeofus · Aug 6, 2012

Gerald C Koch said:
This is just not true you misunderstand the meaning of catalysis. Ascorbate ion reduces oxidized Phenidone/Dimezone back to the parent compound. However this is a moleculae for molecule process not the massive oxidation of the ascorbate that your statement implies.

But in the end it has the effect of a catalyst. Ascorbate, which would reduce silver very slowly on its own if at all (especially at pH of 8), does it rapidly in the presence of trace amounts of Phenidone or Dimezone S. During regular film development, a lot more Ascorbate is oxidized than Phenidone. Curious why this wouldn't count as a catalytic reaction.

Photo Engineer · Aug 6, 2012

Rudi;

With a straight reaction which is what takes place, you get 1 equivalent of AA and 1 eq of Phenidone. If it were catalyzed you might see 100 AA to 1 PD and the PD might be regenerated entirely. This is the case of AA + Iron + Oxygen. You get an Iron catalyzed decomposition of AA which is the bane of all AA developers.

Unless you have a secret ingredient that stops this reaction.....

PE

Gerald C Koch · Aug 6, 2012

But in the end it has the effect of a catalyst.

NO, in a catalytic readtion the catalyst remains unchanged. In the catalytic converter of a car the platinum catalyst can be extracted unchanged when the unit is discarded. It is not used up. Super additivity is NOT a catalytic reaction, the Phenidone or Dimezone does get used up. The regeneration of the Phenidone by the ascorbate is not 100% effective.

When used alone ascorbate ion has a long induction period where no development appears to takr place. This is because it is a negative ion and other negatively charged developer ions behave the same. (An example would be the hydroquinone monosulfonate ion produced by the oxidation of hydroquinone in a sulfite solution.) Given time ascorbate will produce an image. Phenidone and its derivatives have no charge and act more quickly because they are not effected by the charge barrier of the silver halide grains.

I might note that years ago I went around and around with Pat Gainer on this notion and was never able to completely dissabuse him of this idea. I finally gave up.

Rudeofus · Aug 6, 2012

I should say right away that I am no chemist so what I say shall be taken with a big load of salt. Quoting straight from Wikipedia:

Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself.

Even if some of the Phenidone gets used up in the reaction, this is not a key feature of the reaction, and in fact we would all be a lot happier if the Phenidone would not get used up at all. Fact is that lots of silver ions get reduced per active molecule of Phenidone and fact is also that platinum catalysts in cars don't last forever.

But anyway, if Jerry kindly provided me with a link to his exchange with Pat, we might save this forum from a pointless reiteration of arguments that have already been beaten to death. Maybe real chemists have a more precise definition of catalysts that I am not aware of and that would not cover a reaction like reduction of light exposed silver grains with Ascorbate in the presence of traces of Phenidone.

Gerald C Koch · Aug 6, 2012

What happens in a car and also with other metal catalysed reactions is that the catalyst eventually becomes poisoned and no longer works. It does not get used up.

In metal catalysis the catalyst provides a substrate on which the reacting molecule is adborbed. During this adsorption the geometry of the molecule is changed making it more reactive. One can think of the process this way. Consider two muggers, the first (the catalyst) holds the victum down so the other one can get at his pockets more easily. The same thing happens in biochemistry with enzymes. They alter the shape of a molecule causing it to be more reactive.

Fact is that lots of silver ions get reduced per active molecule of Phenidone

This is true only because the ascorbate regenerates the Phenidone by reducing the oxiidized product back to Phenidone. As a result the ascorbate gets oxidized and used up. If you look in a book such as Mason the reactions involved are explained. If Phenidone were a catalyst there would no need for it to be reduced.

Metol also forms a super additive mixture with ascorbate but is less effective since less of it is regenerated than Phenidone.

Chemists don't hold a different definition of catalysis than other people they hold the only definition.

Gerald C Koch · Aug 6, 2012

Rudeofus said:
if Jerry kindly provided me with a link to his exchange with Pat, we might save this forum from a pointless reiteration of arguments that have already been beaten to death

After so many years I have no idea on which thread(s) the exchange occurred. Gainer's argument always returned to saying that it looked like catalysis. Of course looking like something is not the same thing a being the thing.

Photo Engineer · Aug 6, 2012

Jerry is correct.

My example is correct but misleading. I said "PD might be regenerated". Well, it is regenerated but not 100% due to possible alkaline ring opening so I picked a bad example. IDK the amounts of ring opening and regeneration. If you had Dimezone S there, it would be 100% regenerated. PD is partly regenerated and partly hydrolyzed upon oxidation.

That is why I like Dimezone S. It is easier for me to predict.

PE

AlbertZeroK · Aug 7, 2012

Exciting stuff! And just what i need. Wonder how it works on delta 3200?

Mark, once you get a formula with 99% tea, i think i will jump aboard and start doing some testing of my own. I just dumped over 3 liters of dead xtol.

albada · Aug 7, 2012

Alan Johnson said:
Your precipitate may be glycol-borate complex ,we will never know.I don't think esters are formed at the mixing temperatures you use:
http://www.chemicalforums.com/index.php?topic=41216.0
For other PC developer PC-TEA when selecting development times for different films I have used a simple multiplier of Xtol time,is there any reason not to use this with one of the concentrates?

Alan, thanks for the above link. Interesting! His symptoms are identical to mine, even though he's using a different glycol and borate. This gives me more motivation to replace the borate with TEA. BTW, that's what PE told me to do months ago. But I stayed with metaborate because it boosts the solubility of ascorbic acid in propylene glycol. Maybe I shouldn't have...

The single multiplier will probably get you close, but I suspect that films will respond differently to the lower pH, resulting in a different multiplier for each film.

AlbertZeroK said:
Exciting stuff! And just what i need. Wonder how it works on delta 3200?
Mark, once you get a formula with 99% tea, i think i will jump aboard and start doing some testing of my own. I just dumped over 3 liters of dead xtol.

I have the same motivation as you: I hate to discard aging XTOL. The 99% TEA arrives today, so I'll soon be trying it.

Mark Overton

albada · Aug 8, 2012

Rudeofus said:
I would like to know to which extent variations in composition have a visible effect on characteristic courve, grain, sharpness, etc. Since you have obviously done lots of experiments before you came up with your final result, could you comment on that? Would a 10% variation make a big difference or does it take much more before you saw anything different?

An interesting question. I've found that 15% variation in sulfite makes little difference. But 10% too much Phenidone/Dimezone can increase grain noticeably. For a concentrate, it would be helpful if both sulfite and concentrate could be measured by volume, preferably with a set of kitchen measuring spoons (teaspoon/tablespoon) or perhaps a medicine measuring cup. Either way, the sulfite would be less accurate than the liquid due to variations in compaction and fineness of the powder. I think that if a formula can give good results within a +/- 15% error in sulfite, it'll be acceptable.

Medicine measuring cups can be purchased in a 100-pack (!) for under $5 as in this example at Amazon. One advantage of these cups is that you can draw fill-lines at the correct levels with a black felt-tip marker, making measurement of arbitrary quantities easy.

Mark Overton

Photo Engineer · Aug 8, 2012

Measuring viscous liquids by volume becomes tricky! Best to use a syringe from a pet store or vet, or use weight.

As for the variations, you may see little visible difference with Sulfite unless you look at Grain or Sharpness. Things like that can change quickly.

PE

albada · Aug 12, 2012

Photo Engineer said:
Measuring viscous liquids by volume becomes tricky! Best to use a syringe from a pet store or vet, or use weight. PE

Funny you should mention weighing. I find myself weighing all liquids once I know their sg, as in the formula below. For me, it's more accurate.

Here's an interesting discovery:

The pH of a TEA-based developer changes much with temperature.

I know that pH changes with temperature, but I'm used to XTOL and my similar developers that use borate buffers. For them, the change in pH from 20C to 30C is .02 to .04, which is not significant. But when I replaced the borate with TEA, the pH-shift from 20C to 30C was .17, which is substantial. Here's the TEA-based developer I was testing:

80 g Sodium sulfite
8.3 g Ascorbic acid
13.6 g TEA-99%
0.2 g Dimezone-S
20 g Propylene glycol (to simulate a concentrate)
Water to 1 L
(I don't suggest you mix this. pH is too high at 20C and dev-times too short)

As temperature rises, the large pH-drop will partially offset the effect of the rise in temperature. I wonder if such a developer would allow users to be sloppy with temperature-control. Anyway, this aspect of TEA is nice to know about. As always, comments are welcome.

Mark Overton

albada · Aug 13, 2012

Has anyone seen this happen?
This is the same beaker of developer, developing test-strips for 9.5 and then 10.25 minutes:

What's odd is the left half of the curves are identical, despite the time-difference. The right half of the chart behaves as we'd expect. Any idea why?

Mark Overton

Photo Engineer · Aug 13, 2012

albada said:
Has anyone seen this happen?
This is the same beaker of developer, developing test-strips for 9.5 and then 10.25 minutes:

View attachment 55406

What's odd is the left half of the curves are identical, despite the time-difference. The right half of the chart behaves as we'd expect. Any idea why?

Mark Overton

You have probably caught the film at maximum (or optimum) development in the larger faster grains, just before the fog starts. The upper scale is just a bit underdeveloped. Thus the upper scale contrast increases.

This is just a guesstimate, but I have seen something like it before.

PE

Photo Engineer · Aug 13, 2012

Well, this might take place in any developer. You just have to test and see if you are concerned.

PE

Progress on XTOL-concentrate

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