Vitamin C in divided developer?

[Jordan]

I checked the MSDS of ph-up - 99.9% pure anhydrous Sodium Carbonate - I use tap water. Any chemical I can get from a cheaper source I use. Ascorbic Acid is from Trader Joes. Sodium Ascorbate is from a Nutrition Center. - Sodium Chloride is from my kitchen - so is Sodium Bicarbonate. I have never had inconsistant results or chemical failures. I also use a calibrated precision scale accurate to .001g - I just don't see anything that won't work if it is within a tolerance of measurement or purity. I believe that tolerance to be pretty wide.

Please please please let's not go down that road in this thread!

 

[fhovie]

Ok - one last comment and I'll shut up. I write software for process controllers - Kodak is an account of the company I work for. I see the old technology these companies use in PRODUCTION to mix chemicals. - Sclales that are not designed right, out of calibration, antiue electronics. So I make the following observations:
OE photo chemicals are made with no greater precision than I make them - At least I give each batch attention to precision with interest.
Just because it came out of a supermarket box doesn't mean it is not pure. - A good friend of mine is an engineer at US Borax. They don't have a "good" process and a "crappy" process to make chemicals for photography, or soap or for science geeks.
The proof is in the pudding. My processes make good predictable outcomes. Where is the improvement for spending money on reagent grade chemicals? There is NONE. Don't worry, I will not call customer support for Kodak for a homebrew failure (which I have not had yet - ever) - That being said - most of my chemicals come from places like artcraft or the formulary or JohnnyD in Canada. I refuse to buy common walmart items from them. Food grade ascorbic acid or sodium ascorbate is pure enough. Non-iodized salt is fine. pH-UP works great. ArmanHammer Baking Soda is wonderful. Photograde TEA? I hardly think so. Even our developing agents are make by hair color experts. Photo chemicals are for the most part a by-product of making something else.

OK - disagree - spend a bunch - our results will be the same. That is my point. When I have chemical failures I'll listen to you say, "I told you so" But in 10 years it hasn't happened yet.

 

[Photo Engineer]

Well, I worked in that Kodak production area you refer to, and they had millions of dollars worth of high end process control hardware and software for handling the entire making and coating operation.

The chemical synthesis and chemical mix areas were similarly automated.

I'm sure I have no idea what you are referring to, but I doubt if they gave the guided tour to the closed sections of the plant. There were even areas that some of us were not allowed to enter.

PE

 

[Jordan]

Test developers are made for testing purposes, but they are more general purpose developers than DS-10, and they don't contain any active means of retarding oxidation, like DS-10 does. For aging test, I use tech/photo grade stock and tap water in one batch and I split it up into multiple vessels. Then one test agent is added to each vessel. The final pH of each test vessel is adjusted with NaOH. These test solutions contain 50g/L of sulfite and they are probably the largest source of transition metals.

OK, this is what I seem to remember from before. Your alcohols, though, shouldn't perturb the pH very much. Are you having to do a big correction with added NaOH? If so, there may be something fishy about the alcohols.

I was trying to block alcohol groups, and thought about one thing I could try. What I meant by sulfoesterification is to modify ROH to ROSO2OX by the same ideas as what you mentioned. When the alcohol is heated, mixed with sulfamic (amidosulfuric) acid, this should result (X=ammonium). Same could be done with iminodisulphonic acid, etc. Sulfamic acid decomposes at high temp to sulfuric acid and ammonia so I thought to remove the excess agent this way... but the consequence of residual acid can be too messy to get useful insight out of it, and I abandoned the approach.

Wow, you're getting into some serious chemistry. I hope you have the proper facilities. If you need to tie up the ROH, why are you using it at all in the first place? There are "heavy ether" solvents like ethylene glycol dimethyl ether that may be more appropriate.

About Dequest 2000 series you described, that's not what I remember from when we discussed it before... If the agents are available free of phosphates, it might be worth looking into.

I don't really know what the major problem with phosphates is. Do free phosphate complexes of iron make it a super-oxidant? Is the chemistry of the process known? Phosphonates may pose the same problem for the same reason, but there probably isn't much free phosphate in the Dequest stuff. If I remember correctly, the synthesis of these phosphonates doesn't involve any free phosphate.

BUT the agents I've found to be useful so far (and I can at least understand how they work, or at least to corroborate with published data to some extent) use, almost exclusively, nitrogen ligands. Along this line, compounds like bipy are useful if safe and cheap alternatives are found. On the other hand, alkanolamines are convenient, practical agents, and they can inhibit oxidation BUT the way it has to be done is counterintuitive, since they are usually used as alcohol, organic base buffer, or something along that line of use. On the other hand, some of the heterocyclic antifoggant analogues that don't function as antifoggants may be useful. Here, the search process is too involved for me.

If alkanolamines do the job, why not? As long as your level of transition metal impurity is low enough, I see no reason why something like triethanolamine can't be an oxidation inhibitor and a buffer in the same soup at the same time. The quantity lost to the "inhibition pathway" has to be minute relative to what is needed for buffering. With the fake antifoggants and bipy, you're getting into expensive (though interesting) territory...

Presence of phosphate changes the pathway or kinetics of oxidation when peroxide and iron catalyst are present in water. I can read the literature again and come back to you, or send you copies if interested, but what I remember is that, in absence of phosphates, OH. are first involved but this is not detected to the same level when phospate is present. In practice, ascorbate developer containing phosphate can lose ascorbate very fast, and this may happen without discoloration. (Some people might remember my errorneous report years ago when I posted something on this before I run enough testing at various conditions... I regret.)

This explains the above, then. You can just send me the citations or PDFs if you happen to have them. Maybe we should take this off-forum... I get the feeling that the others are falling asleep.

Perhaps the main issue is to find a source of sodium sulfite that is free of transition metals? Are there other sulfites that can do the job?

 

[Kirk Keyes]

Maybe we should take this off-forum... I get the feeling that the others are falling asleep.

I'm still following. No sleeping on the web here.

Kirk

 

[Photo Engineer]

Jordan;

Strong complexing agents tend to reduce the oxidation potential (and color) of transition metal ion complexes. That is why the Ferric-Dequest complex is both colorless, and an extremely weak oxidant. Ferric EDTA is a weaker oxidant than Ferric Chloride which is not complexed.

I even imagined, at the time, that it would be possible to use the Ferric-Dequest couple as an indicator for titration of the ferric ion and complexation with Dequest. I think it is about 10^10 greater than the pKsp of Ferric Hydroxide, which is why it can dissolve the hydroxide. This is powerful stuff. I have suspected that it could cause problems with hemoglobin, by removing iron from it. OTOH, EDTA can be injected into the blood with no deleterious effects to remove heavy metals in cases of metal poisioning, with no harm to hemoglobin.

Of course, I don't have to tell you that, I guess!

PE

 

[Ryuji]

The pH correction for alcohols is usually very small, like 0.05 or on that order. But I also tried various acids in the same run (we are talking about a select group of the entire results I obtained, because this topic was started with propylene glycol, and I saw a curious pattern when compared within alcohols/glycols. this is why the group of alcohols I listed is rather wide-ranging), which required greater correction.

The idea of blocking -OH came from the results we talked about, as well as another set of comparison comparison additives where the main difference was in -OH group. So I thought to see if I could block them and see if the ordering of developer-protective effects remains the same or not, etc. I did /do not know if -OH is/was related. I just guessed so, in the case of propylene glycol, because triethylene glycol had much less effect. (again, more impurity in propylene than triethylene glycol?)

I do not know if anyone knows the exact mechanism of how phosphates get involved. I can look up some industrial chem references to see how those chelators are synthesized when I come to that point.

About the alkanolamine, that is exactly the point and why I said counterintuitive:

"If alkanolamines do the job, why not? As long as your level of transition metal impurity is low enough, I see no reason why something like triethanolamine can't be an oxidation inhibitor and a buffer in the same soup at the same time. The quantity lost to the "inhibition pathway" has to be minute relative to what is needed for buffering."

I agree that would be the most straight-forward, rational thinking. I thought so at first as well. Guess what, I've seen a very curious, counterintuitive phenomenon (well, at least at first) about this. But we should discuss this off list. I'll have refs ready as well.

Regarding nonsulfite antioxidants, hydroxylamines are sometimes used, especially in color developers. But no matter what, the iron impurities in sulfite is on the order of 10ppm, so it seems wisest to design the developer so that it doesn't get rotten when iron comes from some unknown source...

 

[Jordan]

I even imagined, at the time, that it would be possible to use the Ferric-Dequest couple as an indicator for titration of the ferric ion and complexation with Dequest. I think it is about 10^10 greater than the pKsp of Ferric Hydroxide, which is why it can dissolve the hydroxide. This is powerful stuff. I have suspected that it could cause problems with hemoglobin, by removing iron from it. OTOH, EDTA can be injected into the blood with no deleterious effects to remove heavy metals in cases of metal poisioning, with no harm to hemoglobin.

It does indeed sound powerful. But the iron in hemoglobin is held VERY tightly. From what I remember, there is an enzyme whose only role is to insert iron into heme. It is an energy-requiring process in which the enzyme actually deforms the heme plane (this breaks a lot of stabilization). I'll look it up.

 

[Maine-iac]

The proof is in the pudding. My processes make good predictable outcomes. Where is the improvement for spending money on reagent grade chemicals? There is NONE.

At the risk of needlessly extending this line of thought, I'll just say that my experience matches yours. I've been using supermarket/healthfood chemicals (except for the esoteric ones) for years, AND measuring them with teaspoons, and have never had a problem. I even use Arm & Hammer Washing Soda routinely for recipes calling for sodium carbonate, don't adjust for the monohydrate/anhydrous difference, and it makes no difference at all in performance. (I have some anhydrous that I purchased once, so I have compared the two.) Nor have I ever found it significant that I use teaspoons instead of my balance scale which languishes somewhere under the counter in my darkroom. The proof is indeed in the pudding.

Larry

 

[Kirk Keyes]

[...] and it makes no difference at all in performance.

It all depends on what your critieria for successfull performance are. If you have looser criteria you may find no difference in some things, If by success, you mean I can make a print that looks OK, then you are probably right. But if you have tighter criteria, I suspect you will see differences.

 

[Maine-iac]

It all depends on what your critieria for successfull performance are. If you have looser criteria you may find no difference in some things, If by success, you mean I can make a print that looks OK, then you are probably right. But if you have tighter criteria, I suspect you will see differences.

I'm pretty fussy about my prints. They need to be exhibition quality. I want to see a full range of tones, very little to no grain, extremely sharp edges, lots of detail in the shadows and highlights, and rich D-max.

Do I always get that? Does anyone? We all have our clunkers from time to time, or we change our minds about how we want the print to look, or we don't execute well under the enlarger with the right combinations of dodges and burns, but any clunkers I get I can trace to mistakes I've made, not to the lack of precision measurements in the chemistry. I just have not found photo chemistry to be all that precise.

Larry

 

[Ryuji]

I just have not found photo chemistry to be all that precise.

Which is worse?

Imprecise execution of good formula.

or

Precise execution of crappy formula.

It appears to me that you are mixing up the issues of quality of understanding of the problem being solved, ability to utilize tricks in practical chemistry to implement the solution, quality of the agents being used, and the precision of preparing actual solution. They are different problems, although two or more are sometimes dealt with simultaneously.

 

[billtroop]

At last, some good thinking, elegantly if slightly clunkily expres't. I would add that it does come down to cases. By and large, print development will not be substantially impaired by imprecision--and if it is, it is a matter easily repaired. But negative formulas are far more likely to perform poorly if there is the slightest maladjustment. Even so, some negative formulas are less subject to variation than others. For example, if I recall correctly, the original publication of D-23 gave teaspoon equivalents. Henn et al. obviously were not advocating volumetric measurement for all negative developers, far from it. What they had done was to design a very simple formula where imprecisions in volumetric measurement would cause no great harm.

This is not true of the vast majority of negative formulas.

There are so many other considerations. Take for example carefully measured D-76. As Carlton and Crabtree published in 1929, 'with ... D-76 the rate of development increased with keeping. The gamma for 12 minutes development increased from 0.78 to 1.19 in 49 days.'

Needless to say, an increase in gamma from 0.78 to 1.19 is not tolerable by any standard. Such an increase may occur with perfectly mixed D-76 upon standing for 49 days. It may also occur with many other developers when they are mixed with very slight variations or where the chemicals used for that particular batch have deteriorated or exhibit some other kind of irregularity--even if there is no standing of the solution before use. Haist has often remarked that all developers should at the very least specify a target pH. But how many would entertain the notion of pH control or even rough sensitometric control of their development processes?

Which is worse?

Imprecise execution of good formula.

or

Precise execution of crappy formula.

It appears to me that you are mixing up the issues of quality of understanding of the problem being solved, ability to utilize tricks in practical chemistry to implement the solution, quality of the agents being used, and the precision of preparing actual solution. They are different problems, although two or more are sometimes dealt with simultaneously.

 

[Tom Hoskinson]

...But how many would entertain the notion of pH control or even rough sensitometric control of their development processes?

I do and I'm not the only one posting on APUG who does.

 

[Kirk Keyes]

I do and I'm not the only one posting on APUG who does.

I haven't been checking pH, but I have been running a step wedge with every film run I've done for the last year to see how much things change from run to run.

 

[Photo Engineer]

I haven't been checking pH, but I have been running a step wedge with every film run I've done for the last year to see how much things change from run to run.

Kirk, don't keep us in suspense. Tell us what is happening with those curves. I would guess things are pretty good.

PE

 

[sanking]

Haist has often remarked that all developers should at the very least specify a target pH. But how many would entertain the notion of pH control or even rough sensitometric control of their development processes?

Well, you sure would not be talking about me. I check the pH of every working solution I mix, and I frequenly make comparison tests with step wedges of developer stock solutions of different age with sensitomeric control. I would consider any developer that is not capable of duplicating CI to a value of no more than log 0.05 over a period ranging from freshly mixe to 6-12 months old not worthy of consideration for general use. This level of precision is quite feasible with many two part solutions such as PMK and Pyrocat-HD, even when the stock solutions are mixed in distilled water.

Sandy

 

[Alan Johnson]

I shot and printed 11x a film of seascapes on T-max 100 using my experimental formula 2VIT-C 91205 (see my post on p3).It has 2 defects:

1-It prints on grade 1 or 2 instead of 2 or 3.

2-Although it contains no sulfite the grain does not appear large or sharp (no Rodinal look), nor is it any sharper or faster than Emofin.(I am not familiar with Diafine)

An acceptable developer, subject to longevity ,from which I made a print suitable for club competition,but nothing special by way of sharpness or speed from a first test.

 

[Kirk Keyes]

I would consider any developer that is not capable of duplicating CI to a value of no more than log 0.05 over a period ranging from freshly mixe to 6-12 months old not worthy of consideration for general use.

Do you mean your target range for the CI is +/- 0.05 or that you have a target density on the test film that must be within +/- 0.05 Optical Density? If I remember correctly, CI is a ratio and it has no units, log or otherwise.

 

[Kirk Keyes]

It has 2 defects:

Perhaps you should think of it as "failing 2 design goals." :^)

 

[Maine-iac]

But how many would entertain the notion of pH control or even rough sensitometric control of their development processes?

I do. I use pH lab paper rather than a pH meter, but I do know the pH of all the homebrew formulas I concoct. And I certainly agree that pH is one of the more important factors in the success of a formula.

I also agree that there are some developer formulas that demand more precision than others; BUT I have never found one where there was a visible difference, in results from formulas measured with teaspoons and ones measured with a scale.

Measuring with teaspoons is not sloppy; it's not just " a little of this and a pinch of that." Careful measurement and consistency are important for good results. But volumetric measurements are just as legitimate a method as weight measurement, and in the case of some chemicals, may be even better.

Larry

 

[sanking]

Do you mean your target range for the CI is +/- 0.05 or that you have a target density on the test film that must be within +/- 0.05 Optical Density? If I remember correctly, CI is a ratio and it has no units, log or otherwise.

Kirk

You are correct that CI can not be expressed in terms of log units and I apologize for the confusing use of language. What I meant was that the acceptable range should be no more than +/- 0.05 of log density for any given CI value.

For example, if I use a freshly mixed solution of Pyrocat-HD and develop a sheet of JandC 400 exposed to a step table to a target CI of 0.58, and the resulting step densties read from 0.12 at Step 21 to 1.70 at Step 1, I would expect to be able to repeat this result with a six month old solution of the developer with a range of log density readings from 0.12 - 1.65 to 0.12 - 1.75.

On a related note (since Bill Troops' comment about pH and sensitometry is really about consistncy of results), there has been some discussion from time to time as to the portability of development data created by one person when used by another person in a different environment. I have compared the results of my own BTZS testing for a few specific combinations of films and developers to those of the sample files that are included in Phil Davis' Winplotter program, and in most cases have found the range of results to vary by about the same value, i.e. log +/- 0.1, when the targets are expressed in DR. For example, if Davis' sample files suggest that 12 minutes of development in D76 1:1 with rotary agitation at 68º F will produce a negative density range of log 1.7, I would expect my own data to fall within a DR range of 1.6 - 1.8. Obviously one must follow the same develoment protocol (temperature control, dilution, type of agitation, pre-soak if specified, etc.) to achieve this level of precision, but in my opinion it is well within the reach of most careful workers.

Sandy

 

[Alan Johnson]

"Failing two design goals" -Quite so.

In Edge of Darkness p95 Barry Thornton gives a 2 bath formula containing metol/sulfite -A and metaborate -B.

Worth trying metol/vit C -A and metaborate -B possibly?

 

[sanking]

I also agree that there are some developer formulas that demand more precision than others; BUT I have never found one where there was a visible difference, in results from formulas measured with teaspoons and ones measured with a scale.

Measuring with teaspoons is not sloppy; it's not just " a little of this and a pinch of that." Careful measurement and consistency are important for good results. But volumetric measurements are just as legitimate a method as weight measurement, and in the case of some chemicals, may be even better.

Larry

In many formulas with which I have experiemented very small differences in the amount of substances such as potassium bromide, sulphite, phenidone and ascorbic acid can have a really dramatic impact on the results. For example, in a formula that contains pyrogallol or pyrocatechin + phenidone the amount of phenidone needed may be optimized at about 0.01 grams per liter of working solution, and results will be very different if the amount is doubled or halved. How are you going to meausre amounts this small with a teaspoon, even when you multiply them by a factor of 100 to 1000?

 

[Alan Johnson]

Thanks Jay,

I can't get sodium ascorbate at a health food store but they dont exactly have a lot of metaborate either so its back to the photo chemical suppliers.I suppose its not quite vit C but as close as practicable.